csFastFloat 3.0.0

There is a newer version of this package available.
See the version list below for details.
dotnet add package csFastFloat --version 3.0.0
NuGet\Install-Package csFastFloat -Version 3.0.0
This command is intended to be used within the Package Manager Console in Visual Studio, as it uses the NuGet module's version of Install-Package.
<PackageReference Include="csFastFloat" Version="3.0.0" />
For projects that support PackageReference, copy this XML node into the project file to reference the package.
paket add csFastFloat --version 3.0.0
#r "nuget: csFastFloat, 3.0.0"
#r directive can be used in F# Interactive and Polyglot Notebooks. Copy this into the interactive tool or source code of the script to reference the package.
// Install csFastFloat as a Cake Addin
#addin nuget:?package=csFastFloat&version=3.0.0

// Install csFastFloat as a Cake Tool
#tool nuget:?package=csFastFloat&version=3.0.0

csFastFloat : a fast and accurate float parser


C# port of Daniel Lemire's fast_float fully ported from C++ to C#. It is almost 7 times faster than the standard library in some cases while providing exact results.


We use the realistic files in /data. The mesh.txt data file contains numbers that are easier to parse whereas the canada.txt data file is representative of a more challenging scenario. We compare the Double.Parse() function from the runtime library with our FastFloat.ParseDouble() function. The ParseNumberString() only function parses the string itself without any float computation: it might represent an upper bound on the possible performance.

BenchmarkDotNet=v0.12.1, OS=ubuntu 20.04 (container)
AMD EPYC 7262, 1 CPU, 16 logical and 8 physical cores
.NET Core SDK=5.0.102
  [Host]        : .NET Core 5.0.2 (CoreCLR, CoreFX, X64 RyuJIT
  .NET Core 5.0 : .NET Core 5.0.2 (CoreCLR, CoreFX, X64 RyuJIT

Job=.NET Core 5.0  Runtime=.NET Core 5.0

|                     Method |        FileName |      Mean |     Error |    StdDev |       Min | Ratio | MFloat/s |     MB/s |
|--------------------------- |---------------- |----------:|----------:|----------:|----------:|------:|---------:|---------:|
|    FastFloat.ParseDouble() | data/canada.txt |  5.140 ms | 0.0280 ms | 0.0262 ms |  5.105 ms |  0.14 |    21.77 |   408.99 |
| 'ParseNumberString() only' | data/canada.txt |  2.540 ms | 0.0053 ms | 0.0047 ms |  2.531 ms |  0.07 |    43.90 |   824.87 |
|             Double.Parse() | data/canada.txt | 37.147 ms | 0.3284 ms | 0.3071 ms | 36.443 ms |  1.00 |     3.05 |    57.29 |
|                            |                 |           |           |           |           |       |          |          |
|    FastFloat.ParseDouble() |   data/mesh.txt |  2.083 ms | 0.0029 ms | 0.0024 ms |  2.080 ms |  0.29 |    35.10 |   298.07 |
| 'ParseNumberString() only' |   data/mesh.txt |  1.298 ms | 0.0034 ms | 0.0032 ms |  1.294 ms |  0.18 |    56.45 |   479.30 |
|             Double.Parse() |   data/mesh.txt |  7.086 ms | 0.0911 ms | 0.0852 ms |  6.931 ms |  1.00 |    10.54 |    89.45 |


.NET Core 3.1 or better. Under .NET 5 framework, the library takes advantage of the new Math.BigMul() function. Since v2.0, net standard 2.0 is supported.


Two functions are available: FastDoubleParser.ParseDouble and FastFloatParser.ParseFloat. Since v3.0, TryParse pattern is supported for each function.

String, char * and ReadOnlySpan<char> are supported inputs.

using csFastFloat;

double x;
float y;
double answer = 0;
foreach (string l in lines)
        x = FastDoubleParser.ParseDouble(l);
        y = FastFloatParser.ParseFloat(l);

Input strings are expected to be valid UTF-16.

Trailing content in the string is ignored. You may pass an optional out int characters_consumed parameter FastDoubleParser.ParseDouble(l, out int characters_consumed) if you wich to check how many characters were processed. Some users may want to fail when the number of characters consumed does not match the string length.

For UTF-8 or ASCII inputs, you may pass a ReadOnlySpan<byte> argument. You can also pass an optional out int characters_consumed parameter to track the number of characters consumed by the number pattern.


This library is the main project in my master's degree under the direction of Professor Daniel Lemire at TELUQ University. A special thanks to Egor Bogatov and all contributors for their really meaningful contribution.


Product Compatible and additional computed target framework versions.
.NET net5.0 is compatible.  net5.0-windows was computed.  net6.0 was computed.  net6.0-android was computed.  net6.0-ios was computed.  net6.0-maccatalyst was computed.  net6.0-macos was computed.  net6.0-tvos was computed.  net6.0-windows was computed.  net7.0 was computed.  net7.0-android was computed.  net7.0-ios was computed.  net7.0-maccatalyst was computed.  net7.0-macos was computed.  net7.0-tvos was computed.  net7.0-windows was computed.  net8.0 was computed.  net8.0-android was computed.  net8.0-browser was computed.  net8.0-ios was computed.  net8.0-maccatalyst was computed.  net8.0-macos was computed.  net8.0-tvos was computed.  net8.0-windows was computed. 
.NET Core netcoreapp2.0 was computed.  netcoreapp2.1 was computed.  netcoreapp2.2 was computed.  netcoreapp3.0 was computed.  netcoreapp3.1 is compatible. 
.NET Standard netstandard2.0 is compatible.  netstandard2.1 was computed. 
.NET Framework net461 was computed.  net462 was computed.  net463 was computed.  net47 was computed.  net471 was computed.  net472 was computed.  net48 was computed.  net481 was computed. 
MonoAndroid monoandroid was computed. 
MonoMac monomac was computed. 
MonoTouch monotouch was computed. 
Tizen tizen40 was computed.  tizen60 was computed. 
Xamarin.iOS xamarinios was computed. 
Xamarin.Mac xamarinmac was computed. 
Xamarin.TVOS xamarintvos was computed. 
Xamarin.WatchOS xamarinwatchos was computed. 
Compatible target framework(s)
Included target framework(s) (in package)
Learn more about Target Frameworks and .NET Standard.

NuGet packages (3)

Showing the top 3 NuGet packages that depend on csFastFloat:

Package Downloads

World's Fastest .NET CSV Parser. Modern, minimal, fast, zero allocation, reading and writing of separated values (csv, tsv etc.). Cross-platform, trimmable and AOT/NativeAOT compatible.


API for game Geometry Dash


Plist API that allows to serialize and deserialize directly as a specific objects

GitHub repositories (2)

Showing the top 2 popular GitHub repositories that depend on csFastFloat:

Repository Stars
World's Fastest .NET CSV Parser. Modern, minimal, fast, zero allocation, reading and writing of separated values (`csv`, `tsv` etc.). Cross-platform, trimmable and AOT/NativeAOT compatible.
Main repository for the stark compiler frontend + vscode integration + language specs
Version Downloads Last updated
4.1.4 77,706 4/20/2024
4.1.3 256 4/20/2024
4.1.2 1,552 4/9/2024
4.1.0 1,408,848 11/6/2021
4.0.0 827 10/22/2021
3.0.0 2,289 3/15/2021
2.0.0 944 3/5/2021
1.0.0 1,059 2/22/2021