Asked 2023-09-20 20:30:48 View
782,253

What is the difference between `decimal`

, `float`

and `double`

in .NET?

When would someone use one of these?

- interesting article zetcode.com/lang/csharp/datatypes - anyone
- You cannot use decimal to interop with native code since it is a .net specific implementation, while float and double numbers can be processed by CPUs directly. - anyone

`float`

(the C# alias for `System.Single`

) and `double`

(the C# alias for `System.Double`

) are floating *binary* point types. `float`

is 32-bit; `double`

is 64-bit. In other words, they represent a number like this:

```
10001.10010110011
```

The binary number and the location of the binary point are both encoded within the value.

`decimal`

(the C# alias for `System.Decimal`

) is a floating *decimal* point type. In other words, they represent a number like this:

```
12345.65789
```

Again, the number and the location of the *decimal* point are both encoded within the value – that's what makes `decimal`

still a floating point type instead of a fixed point type.

The important thing to note is that humans are used to representing non-integers in a decimal form, and expect exact results in decimal representations; not all decimal numbers are exactly representable in binary floating point – 0.1, for example – so if you use a binary floating point value you'll actually get an approximation to 0.1. You'll still get approximations when using a floating decimal point as well – the result of dividing 1 by 3 can't be exactly represented, for example.

As for what to use when:

For values which are "naturally exact decimals" it's good to use

`decimal`

. This is usually suitable for any concepts invented by humans: financial values are the most obvious example, but there are others too. Consider the score given to divers or ice skaters, for example.For values which are more artefacts of nature which can't really be measured

*exactly*anyway,`float`

/`double`

are more appropriate. For example, scientific data would usually be represented in this form. Here, the original values won't be "decimally accurate" to start with, so it's not important for the expected results to maintain the "decimal accuracy". Floating binary point types are much faster to work with than decimals.

Answered 2023-09-20 20:30:48

`float`

/`double`

usually do not represent numbers as`101.101110`

, normally it is represented as something like`1101010 * 2^(01010010)`

- an exponent - anyone- @Hazzard: That's what the "and the location of the binary point" part of the answer means. - anyone
- I'm surprised it hasn't been said already,
`float`

is a C# alias keyword and isn't a .Net type. it's`System.Single`

..`single`

and`double`

are floating binary point types. - anyone - @BKSpurgeon: Well, only in the same way that you can say that
*everything*is a binary type, at which point it becomes a fairly useless definition. Decimal is a decimal type in that it's a number represented as an integer significand and a scale, such that the result is significand * 10^scale, whereas float and double are significand * 2^scale. You take a number written in decimal, and move the decimal point far enough to the right that you've got an integer to work out the significand and the scale. For float/double you'd start with a number written in binary. - anyone - Another difference: float 32-bit; double 64-bit; and decimal 128-bit. - anyone

Precision is the main difference.

Float - 7 digits (32 bit)

Double-15-16 digits (64 bit)

Decimal -28-29 significant digits (128 bit)

Decimals have much higher precision and are usually used within financial applications that require a high degree of accuracy. Decimals are much slower (up to 20X times in some tests) than a double/float.

Decimals and Floats/Doubles cannot be compared without a cast whereas Floats and Doubles can. Decimals also allow the encoding or trailing zeros.

```
float flt = 1F/3;
double dbl = 1D/3;
decimal dcm = 1M/3;
Console.WriteLine("float: {0} double: {1} decimal: {2}", flt, dbl, dcm);
```

Result :

```
float: 0.3333333
double: 0.333333333333333
decimal: 0.3333333333333333333333333333
```

Answered 2023-09-20 20:30:48

- @Thecrocodilehunter: sorry, but no. Decimal can represent all numbers that can be represented in decimal notation, but not 1/3 for example. 1.0m / 3.0m will evaluate to 0.33333333... with a large but finite number of 3s at the end. Multiplying it by 3 will not return an exact 1.0. - anyone
- @Thecrocodilehunter: I think you're confusing accuracy and precision. They are different things in this context. Precision is the number of digits available to represent a number. The more precision, the less you need to round. No data type has infinite precision. - anyone
- @Thecrocodilehunter: You're assuming that the value that is being measured is
*exactly*`0.1`

-- that is rarely the case in the real world!*Any*finite storage format will conflate an infinite number of possible values to a finite number of bit patterns. For example,`float`

will conflate`0.1`

and`0.1 + 1e-8`

, while`decimal`

will conflate`0.1`

and`0.1 + 1e-29`

. Sure,*within a given range*, certain values can be represented in any format with zero loss of accuracy (e.g.`float`

can store any integer up to 1.6e7 with zero loss of accuracy) -- but that's still not*infinite*accuracy. - anyone - @Thecrocodilehunter: You missed my point.
`0.1`

is**not a special value**! The only thing that makes`0.1`

"better" than`0.10000001`

is because**human beings**like base 10. And even with a`float`

value, if you initialize two values with`0.1`

the same way,*they will both be the same value*. It's just that that value won't be**exactly**`0.1`

-- it will be*the closest value to*. Sure, with binary floats,`0.1`

that can be exactly represented as a`float`

`(1.0 / 10) * 10 != 1.0`

, but with decimal floats,`(1.0 / 3) * 3 != 1.0`

either.**Neither**is*perfectly*precise. - anyone - @Thecrocodilehunter: You still don't understand. I don't know how to say this any more plainly: In C, if you do
`double a = 0.1; double b = 0.1;`

then`a == b`

**will be true**. It's just that`a`

and`b`

will*both*not exactly equal`0.1`

. In C#, if you do`decimal a = 1.0m / 3.0m; decimal b = 1.0m / 3.0m;`

then`a == b`

will also be true. But in that case,**neither**of`a`

nor`b`

will**exactly**equal`1/3`

-- they will both equal`0.3333...`

. In*both*cases, some accuracy is lost due to representation. You stubbornly say that`decimal`

has "infinite" precision, which is*false*. - anyone

```
+---------+----------------+---------+----------+---------------------------------------------------------+
| C# | .Net Framework | Signed? | Bytes | Possible Values |
| Type | (System) type | | Occupied | |
+---------+----------------+---------+----------+---------------------------------------------------------+
| sbyte | System.Sbyte | Yes | 1 | -128 to 127 |
| short | System.Int16 | Yes | 2 | -32,768 to 32,767 |
| int | System.Int32 | Yes | 4 | -2,147,483,648 to 2,147,483,647 |
| long | System.Int64 | Yes | 8 | -9,223,372,036,854,775,808 to 9,223,372,036,854,775,807 |
| byte | System.Byte | No | 1 | 0 to 255 |
| ushort | System.Uint16 | No | 2 | 0 to 65,535 |
| uint | System.UInt32 | No | 4 | 0 to 4,294,967,295 |
| ulong | System.Uint64 | No | 8 | 0 to 18,446,744,073,709,551,615 |
| float | System.Single | Yes | 4 | Approximately ±1.5e-45 to ±3.4e38 |
| | | | | with ~6-9 significant figures |
| double | System.Double | Yes | 8 | Approximately ±5.0e-324 to ±1.7e308 |
| | | | | with ~15-17 significant figures |
| decimal | System.Decimal | Yes | 16 | Approximately ±1.0e-28 to ±7.9e28 |
| | | | | with 28-29 significant figures |
| char | System.Char | N/A | 2 | Any Unicode character (16 bit) |
| bool | System.Boolean | N/A | 1 / 2 | true or false |
+---------+----------------+---------+----------+---------------------------------------------------------+
```

Answered 2023-09-20 20:30:48

- You left out the biggest difference, which is the base used for the decimal type (decimal is stored as base 10, all other numeric types listed are base 2). - anyone
- The value ranges for the Single and Double are not depicted correctly in the above image or the source forum post. Since we can't easily superscript the text here, use the caret character: Single should be 10^-45 and 10^38, and Double should be 10^-324 and 10^308. Also, MSDN has the float with a range of -3.4x10^38 to +3.4x10^38. Search MSDN for System.Single and System.Double in case of link changes. Single: msdn.microsoft.com/en-us/library/b1e65aza.aspx Double: msdn.microsoft.com/en-us/library/678hzkk9.aspx - anyone
- Decimal is 128 bits ... means it occupies 16 bytes not 12 - anyone

The Decimal structure is strictly geared to financial calculations requiring accuracy, which are relatively intolerant of rounding. Decimals are not adequate for scientific applications, however, for several reasons:

- A certain loss of precision is acceptable in many scientific calculations because of the practical limits of the physical problem or artifact being measured. Loss of precision is not acceptable in finance.
- Decimal is much (much) slower than float and double for most operations, primarily because floating point operations are done in binary, whereas Decimal stuff is done in base 10 (i.e. floats and doubles are handled by the FPU hardware, such as MMX/SSE, whereas decimals are calculated in software).
- Decimal has an unacceptably smaller value range than double, despite the fact that it supports more digits of precision. Therefore, Decimal can't be used to represent many scientific values.

Answered 2023-09-20 20:30:48

- If you're doing financial calculations, you absolutely have to roll your own datatypes or find a good library that matches your exact needs. Accuracy in a financial setting is defined by (human) standards bodies and they have very specific localized (both in time and geography) rules about how to do calculations. Things like correct rounding aren't captured in the simple numeric datatypes in .Net. The ability to do calculations is only a very small part of the puzzle. - anyone

I won't reiterate tons of good (and some bad) information already answered in other answers and comments, but I will answer your followup question with a tip:

When would someone use one of these?

Use decimal for **counted** values

Use float/double for **measured** values

Some examples:

money (do we count money or measure money?)

distance (do we count distance or measure distance? *)

scores (do we count scores or measure scores?)

We always count money and should never measure it. We usually measure distance. We often count scores.

* In some cases, what I would call *nominal distance*, we may indeed want to 'count' distance. For example, maybe we are dealing with country signs that show distances to cities, and we know that those distances never have more than one decimal digit (xxx.x km).

Answered 2023-09-20 20:30:48

- I really like this answer, especially the question "do we count or measure money?" However, other than money, I can't think of anything that is "counted" that is not simply integer. I have seen some applications that use decimal simply because double has
*too few*significant digits. In other words, decimal might be used because C# does not have a**quadruple**type en.wikipedia.org/wiki/Quadruple-precision_floating-point_format - anyone

`float`

7 digits of precision

`double`

has about 15 digits of precision

`decimal`

has about 28 digits of precision

If you need better accuracy, use double instead of float. In modern CPUs both data types have almost the same performance. The only benifit of using float is they take up less space. Practically matters only if you have got many of them.

I found this is interesting. What Every Computer Scientist Should Know About Floating-Point Arithmetic

Answered 2023-09-20 20:30:48

- @RogerLipscombe: I would consider
`double`

proper in accounting applications in those cases (and basically only those cases) where no integer type larger than 32 bits was available, and the`double`

was being used as though it were a 53-bit integer type (e.g. to hold a whole number of pennies, or a whole number of hundredths of a cent). Not much use for such things nowadays, but many languages gained the ability to use double-precision floating-point values long before they gained 64-bit (or in some cases even 32-bit!) integer math. - anyone - Your answer implies precision is the only difference between these data types. Given binary floating point arithmetic is typically implemented in
*hardware FPU*, performance is a significant difference. This may be inconsequential for some applications, but is critical for others. - anyone - @supercat double is
*never*proper in accounting applications. Because Double can only approximate decimal values (even within the range of its own precision). This is because double stores the values in a base-2 (binary)-centric format. - anyone - @BrainSlugs83: Use of floating-point types to hold
*non-whole-number*quantities would be improper, but it was historically very common for languages to have floating-point types that could precisely represent larger whole-number values than their integer types could represent. Perhaps the most extreme example was Turbo-87 whose only integer types were limited to -32768 to +32767, but whose`Real`

could IIRC represent values up to 1.8E+19 with unit precision. I would think it would be much saner for an accounting application to use`Real`

to represent a whole number of pennies than... - anyone - ...for it to try to perform multi-precision math using a bunch of 16-bit values. For most other languages the difference wasn't that extreme, but for a long time it has been very common for languages not to have any integer type that went beyond 4E9 but have a
`double`

type which had unit accuracy up to 9E15. If one needs to store whole numbers which are bigger than the largest available integer type, using`double`

is apt to be simpler and more efficient than trying to fudge multi-precision math, especially given that while processors have instructions to perform 16x16->32 or... - anyone

No one has mentioned that

In default settings, Floats (System.Single) and doubles (System.Double) will never use overflow checking while Decimal (System.Decimal) will always use overflow checking.

I mean

```
decimal myNumber = decimal.MaxValue;
myNumber += 1;
```

throws **OverflowException**.

But these do not:

```
float myNumber = float.MaxValue;
myNumber += 1;
```

&

```
double myNumber = double.MaxValue;
myNumber += 1;
```

Answered 2023-09-20 20:30:48

`float.MaxValue+1 == float.MaxValue`

, just as`decimal.MaxValue+0.1D == decimal.MaxValue`

. Perhaps you meant something like`float.MaxValue*2`

? - anyone- @supercar But it is not true that decimal.MaxValue + 1 == decimal.MaxValue - anyone
- @supercar decimal.MaxValue + 0.1m == decimal.MaxValue ok - anyone
- The
`System.Decimal`

throws an exception just before it becomes unable to distinguish whole units, but if an application is supposed to be dealing with e.g. dollars and cents, that could be too late. - anyone

Integers, as was mentioned, are whole numbers. They can't store the point something, like .7, .42, and .007. If you need to store numbers that are not whole numbers, you need a different type of variable. You can use the double type or the float type. You set these types of variables up in exactly the same way: instead of using the word `int`

, you type `double`

or `float`

. Like this:

```
float myFloat;
double myDouble;
```

(`float`

is short for "floating point", and just means a number with a point something on the end.)

The difference between the two is in the size of the numbers that they can hold. For `float`

, you can have up to 7 digits in your number. For `double`

s, you can have up to 16 digits. To be more precise, here's the official size:

```
float: 1.5 × 10^-45 to 3.4 × 10^38
double: 5.0 × 10^-324 to 1.7 × 10^308
```

`float`

is a 32-bit number, and `double`

is a 64-bit number.

Double click your new button to get at the code. Add the following three lines to your button code:

```
double myDouble;
myDouble = 0.007;
MessageBox.Show(myDouble.ToString());
```

Halt your program and return to the coding window. Change this line:

```
myDouble = 0.007;
myDouble = 12345678.1234567;
```

Run your programme and click your double button. The message box correctly displays the number. Add another number on the end, though, and C# will again round up or down. The moral is if you want accuracy, be careful of rounding!

Answered 2023-09-20 20:30:48

- The "point something" you mentioned is generally referred to as "the fractional part" of a number. "Floating point" does not mean "a number with a point something on the end"; but instead "Floating Point" distinguishes the type of number, as opposed to a "Fixed Point" number (which can also store a fractional value); the difference is whether the precision is fixed, or floating. -- Floating point numbers give you a much bigger dynamic range of values (Min and Max), at the cost of precision, whereas a fixed point numbers give you a constant amount of precision at the cost of range. - anyone

- Double and float can be divided by integer zero without an exception at both compilation and run time.
- Decimal cannot be divided by integer zero. Compilation will always fail if you do that.

Answered 2023-09-20 20:30:48

- They sure can! They also also have a couple of "magic" values such as Infinity, Negative Infinity, and NaN (not a number) which make it very useful for detecting vertical lines while computing slopes... Further, if you need to decide between calling float.TryParse, double.TryParse, and decimal.TryParse (to detect if a string is a number, for example), I recommend using double or float, as they will parse "Infinity", "-Infinity", and "NaN" properly, whereas decimal will not. - anyone
*Compilation*only fails if you attempt to divide a literal`decimal`

by zero (CS0020), and the same is true of integral literals. However if a runtime decimal value is divided by zero, you'll get an exception not a compile error. - anyone

- float: ±1.5 x 10^-45 to ±3.4 x 10^38 (~7 significant figures
- double: ±5.0 x 10^-324 to ±1.7 x 10^308 (15-16 significant figures)
- decimal: ±1.0 x 10^-28 to ±7.9 x 10^28 (28-29 significant figures)

Answered 2023-09-20 20:30:48

- The difference is more than just precision. --
`decimal`

is actually stored in decimal format (as opposed to base 2; so it won't lose or round digits due to conversion between the two numeric systems); additionally,`decimal`

has no concept of special values such as NaN, -0, ∞, or -∞. - anyone

This has been an interesting thread for me, as today, we've just had a nasty little bug, concerning `decimal`

having less precision than a `float`

.

In our C# code, we are reading numeric values from an Excel spreadsheet, converting them into a `decimal`

, then sending this `decimal`

back to a Service to save into a *SQL Server* database.

```
Microsoft.Office.Interop.Excel.Range cell = …
object cellValue = cell.Value2;
if (cellValue != null)
{
decimal value = 0;
Decimal.TryParse(cellValue.ToString(), out value);
}
```

Now, for *almost all* of our Excel values, this worked beautifully. But for some, very small Excel values, using ** decimal.TryParse** lost the value completely. One such example is

cellValue =

**0.00006317592***Decimal.TryParse(cellValue.ToString(), out value);*// would return**0**

The solution, bizarrely, was to convert the Excel values into a `double`

first, and then into a `decimal`

:

```
Microsoft.Office.Interop.Excel.Range cell = …
object cellValue = cell.Value2;
if (cellValue != null)
{
double valueDouble = 0;
double.TryParse(cellValue.ToString(), out valueDouble);
decimal value = (decimal) valueDouble;
…
}
```

Even though `double`

has less precision than a `decimal`

, this actually ensured small numbers would still be recognised. For some reason, ** double.TryParse** was actually able to retrieve such small numbers, whereas

`decimal.TryParse`

Odd. Very odd.

Answered 2023-09-20 20:30:48

- Out of curiosity, what was the raw value of cellValue.ToString()? Decimal.TryParse("0.00006317592", out val) seems to work... - anyone
- -1 Don't get me wrong, if true, it's very interesting but this is a separate question, it's certainly not an answer to this question. - anyone
- Maybe because the Excel cell was returning a double and ToString() value was "6.31759E-05" therefore the decimal.Parse() didn't like the notation. I bet if you checked the return value of Decimal.TryParse() it would have been false. - anyone
- @weston Answers often complement other answers by filling in nuances they have missed. This answer highlights a difference in terms of parsing. It is very much an answer to the question! - anyone
- Er...
`decimal.Parse("0.00006317592")`

works -- you've got something else going on. -- Possibly scientific notation? - anyone

The Decimal, Double, and Float variable types are different in the way that they store the values. Precision is the main difference where float is a single precision (32 bit) floating point data type, double is a double precision (64 bit) floating point data type and decimal is a 128-bit floating point data type.

Float - 32 bit (7 digits)

Double - 64 bit (15-16 digits)

Decimal - 128 bit (28-29 significant digits)

More about...the difference between Decimal, Float and Double

Answered 2023-09-20 20:30:48

- Someone knows why these different digits range for every type? - anyone

For applications such as games and embedded systems where memory and performance are both critical, float is usually the numeric type of choice as it is faster and half the size of a double. Integers used to be the weapon of choice, but floating point performance has overtaken integer in modern processors. Decimal is right out!

Answered 2023-09-20 20:30:48

- Pretty much all modern systems, even cell phones, have hardware support for double; and if you game has even simple physics, you will notice a big difference between double and float. (For example, calculating the velocity / friction in a simple Asteroids clone, doubles allow acceleration to flow much more fluidly than float. -- Seems like it shouldn't matter, but it totally does.) - anyone
- Doubles are also double the size of floats, meaning you need to chew through twice as much data, which hurts your cache performance. As always, measure and proceed accordingly. - anyone

The problem with all these types is that a certain imprecision subsists AND that this problem can occur with small decimal numbers like in the following example

```
Dim fMean as Double = 1.18
Dim fDelta as Double = 0.08
Dim fLimit as Double = 1.1
If fMean - fDelta < fLimit Then
bLower = True
Else
bLower = False
End If
```

Question: Which value does bLower variable contain ?

Answer: On a 32 bit machine bLower contains TRUE !!!

If I replace Double by Decimal, bLower contains FALSE which is the good answer.

In double, the problem is that fMean-fDelta = 1.09999999999 that is lower that 1.1.

Caution: I think that same problem can certainly exists for other number because Decimal is only a double with higher precision and the precision has always a limit.

In fact, Double, Float and Decimal correspond to BINARY decimal in COBOL !

It is regrettable that other numeric types implemented in COBOL don't exist in .Net. For those that don't know COBOL, there exist in COBOL following numeric type

```
BINARY or COMP like float or double or decimal
PACKED-DECIMAL or COMP-3 (2 digit in 1 byte)
ZONED-DECIMAL (1 digit in 1 byte)
```

Answered 2023-09-20 20:30:48

In simple words:

- The Decimal, Double, and Float variable types are different in the way that they store the values.
- Precision is the
(Notice that this is not the single difference) where*main difference***float**is a single precision (32 bit) floating point data type,**double**is a double precision (64 bit) floating point data type and**decimal**is a 128-bit floating point data type. - The summary table:

```
/==========================================================================================
Type Bits Have up to Approximate Range
/==========================================================================================
float 32 7 digits -3.4 × 10 ^ (38) to +3.4 × 10 ^ (38)
double 64 15-16 digits ±5.0 × 10 ^ (-324) to ±1.7 × 10 ^ (308)
decimal 128 28-29 significant digits ±7.9 x 10 ^ (28) or (1 to 10 ^ (28)
/==========================================================================================
```

You can read more here, Float, Double, and Decimal.Answered 2023-09-20 20:30:48

- What does this answer add that isn't already covered in the existing answers? BTW, your "or" in the "decimal" line is incorrect: the slash in the web page that you're copying from indicates division rather than an alternative. - anyone
- And I'd dispute strongly that precision is the main difference. The main difference is the base: decimal floating-point versus binary floating-point. That difference is what makes
`Decimal`

suitable for financial applications, and it's the main criterion to use when deciding between`Decimal`

and`Double`

. It's rare that`Double`

precision isn't enough for scientific applications, for example (and`Decimal`

is often*unsuitable*for scientific applications because of its limited range). - anyone

The main difference between each of these is the precision.

`float`

is a 32-bit number`double`

is a 64-bit number`decimal`

is a 128-bit number

Answered 2023-09-20 20:30:48

**Float:**

It is a floating binary point type variable. Which means it represents a number in it’s binary form. **Float** is a single precision `32 bits(6-9 significant figures)`

data type. It is used mostly in graphic libraries because of very high demand for processing power, and also in conditions where rounding errors are not very important.

**Double:**

It is also a floating binary point type variable with double precision and `64 bits size(15-17 significant figures)`

. Double are probably the most generally used data type for real values, except for financial applications and places where high accuracy is desired.

**Decimal:**

It is a floating decimal point type variable. Which means it represents a number using decimal numbers `(0-9)`

. It uses `128 bits(28-29 significant figures)`

for storing and representing data. Therefore, it has more precision than float and double. They are mostly used in financial applications because of their high precision and easy to avoid rounding errors.

**Example:**

```
using System;
public class GFG {
static public void Main()
{
double d = 0.42e2; //double data type
Console.WriteLine(d); // output 42
float f = 134.45E-2f; //float data type
Console.WriteLine(f); // output: 1.3445
decimal m = 1.5E6m; //decimal data type
Console.WriteLine(m); // output: 1500000
}
}
```

**No. of Bits used:**

- Float uses 32 bits to represent data.
- Double uses 64 bits to represent data.
- Decimal uses 128 bits to represent data.

**Range of values:**

The float value ranges from approximately ±1.5e-45 to ±3.4e38.

The double value ranges from approximately ±5.0e-324 to ±1.7e308.

The Decimal value ranges from approximately ±1.0e-28 to ±7.9e28.

**Precision:**

- Float represent data with single precision.
- Double represent data with double precision.
- Decimal has higher precision than float and Double.

**Accuracy:**

- Float is less accurate than Double and Decimal.
- Double is more accurate than Float but less accurate than Decimal.
- Decimal is more accurate than Float and Double.

Answered 2023-09-20 20:30:48

you must mention values as:

```
Decimal dec = 12M/6;
Double dbl = 11D/6;
float fl = 15F/6;
```

and check the results.

```
Float - 4
Double - 8
Decimal - 12
```

Answered 2023-09-20 20:30:48

- The question was asking for the difference and advantages/disadvantages of each - anyone