How do I get a human-readable file size in bytes abbreviation using .NET?
C#.Netvb.netFilesizeHuman ReadableC# Problem Overview
How do I get a human-readable file size in bytes abbreviation using .NET?
Example: Take input 7,326,629 and display 6.98 MB
C# Solutions
Solution 1 - C#
This may not the most efficient or optimized way to do it, but it's easier to read if you are not familiar with log maths, and should be fast enough for most scenarios.
string[] sizes = { "B", "KB", "MB", "GB", "TB" };
double len = new FileInfo(filename).Length;
int order = 0;
while (len >= 1024 && order < sizes.Length - 1) {
order++;
len = len/1024;
}
// Adjust the format string to your preferences. For example "{0:0.#}{1}" would
// show a single decimal place, and no space.
string result = String.Format("{0:0.##} {1}", len, sizes[order]);
Solution 2 - C#
using Log to solve the problem....
static String BytesToString(long byteCount)
{
string[] suf = { "B", "KB", "MB", "GB", "TB", "PB", "EB" }; //Longs run out around EB
if (byteCount == 0)
return "0" + suf[0];
long bytes = Math.Abs(byteCount);
int place = Convert.ToInt32(Math.Floor(Math.Log(bytes, 1024)));
double num = Math.Round(bytes / Math.Pow(1024, place), 1);
return (Math.Sign(byteCount) * num).ToString() + suf[place];
}
Also in C#, but should be a snap to convert. Also I rounded to 1 decimal place for readability.
Basically determine the number of decimal places in Base 1024 and then divide by 1024^decimalplaces.
And some samples of use and output:
Console.WriteLine(BytesToString(9223372036854775807)); //Results in 8EB
Console.WriteLine(BytesToString(0)); //Results in 0B
Console.WriteLine(BytesToString(1024)); //Results in 1KB
Console.WriteLine(BytesToString(2000000)); //Results in 1.9MB
Console.WriteLine(BytesToString(-9023372036854775807)); //Results in -7.8EB
Edit:
Was pointed out that I missed a Math.Floor, so I incorporated it. (Convert.ToInt32 uses rounding, not truncating and that's why Floor is necessary.) Thanks for the catch.
Edit2:
There were a couple of comments about negative sizes and 0 byte sizes, so I updated to handle those cases.
Solution 3 - C#
A tested and significantly optimized version of the requested function is posted here:
[C# Human Readable File Size - Optimized Function][1]
Source code:
// Returns the human-readable file size for an arbitrary, 64-bit file size
// The default format is "0.### XB", e.g. "4.2 KB" or "1.434 GB"
public string GetBytesReadable(long i)
{
// Get absolute value
long absolute_i = (i < 0 ? -i : i);
// Determine the suffix and readable value
string suffix;
double readable;
if (absolute_i >= 0x1000000000000000) // Exabyte
{
suffix = "EB";
readable = (i >> 50);
}
else if (absolute_i >= 0x4000000000000) // Petabyte
{
suffix = "PB";
readable = (i >> 40);
}
else if (absolute_i >= 0x10000000000) // Terabyte
{
suffix = "TB";
readable = (i >> 30);
}
else if (absolute_i >= 0x40000000) // Gigabyte
{
suffix = "GB";
readable = (i >> 20);
}
else if (absolute_i >= 0x100000) // Megabyte
{
suffix = "MB";
readable = (i >> 10);
}
else if (absolute_i >= 0x400) // Kilobyte
{
suffix = "KB";
readable = i;
}
else
{
return i.ToString("0 B"); // Byte
}
// Divide by 1024 to get fractional value
readable = (readable / 1024);
// Return formatted number with suffix
return readable.ToString("0.### ") + suffix;
}
[1]: http://www.somacon.com/p576.php "C# Human Readable File Size - Optimized Function"
Solution 4 - C#
[DllImport ( "Shlwapi.dll", CharSet = CharSet.Auto )]
public static extern long StrFormatByteSize (
long fileSize
, [MarshalAs ( UnmanagedType.LPTStr )] StringBuilder buffer
, int bufferSize );
/// <summary>
/// Converts a numeric value into a string that represents the number expressed as a size value in bytes, kilobytes, megabytes, or gigabytes, depending on the size.
/// </summary>
/// <param name="filelength">The numeric value to be converted.</param>
/// <returns>the converted string</returns>
public static string StrFormatByteSize (long filesize) {
StringBuilder sb = new StringBuilder( 11 );
StrFormatByteSize( filesize, sb, sb.Capacity );
return sb.ToString();
}
From: http://www.pinvoke.net/default.aspx/shlwapi/StrFormatByteSize.html
Solution 5 - C#
Checkout the ByteSize library. It's the System.TimeSpan for bytes!
It handles the conversion and formatting for you.
var maxFileSize = ByteSize.FromKiloBytes(10);
maxFileSize.Bytes;
maxFileSize.MegaBytes;
maxFileSize.GigaBytes;
It also does string representation and parsing.
// ToString
ByteSize.FromKiloBytes(1024).ToString(); // 1 MB
ByteSize.FromGigabytes(.5).ToString(); // 512 MB
ByteSize.FromGigabytes(1024).ToString(); // 1 TB
// Parsing
ByteSize.Parse("5b");
ByteSize.Parse("1.55B");
Solution 6 - C#
One more way to skin it, without any kind of loops and with negative size support (makes sense for things like file size deltas):
public static class Format
{
static string[] sizeSuffixes = {
"B", "KB", "MB", "GB", "TB", "PB", "EB", "ZB", "YB" };
public static string ByteSize(long size)
{
Debug.Assert(sizeSuffixes.Length > 0);
const string formatTemplate = "{0}{1:0.#} {2}";
if (size == 0)
{
return string.Format(formatTemplate, null, 0, sizeSuffixes[0]);
}
var absSize = Math.Abs((double)size);
var fpPower = Math.Log(absSize, 1000);
var intPower = (int)fpPower;
var iUnit = intPower >= sizeSuffixes.Length
? sizeSuffixes.Length - 1
: intPower;
var normSize = absSize / Math.Pow(1000, iUnit);
return string.Format(
formatTemplate,
size < 0 ? "-" : null, normSize, sizeSuffixes[iUnit]);
}
}
And here is the test suite:
[TestFixture] public class ByteSize
{
[TestCase(0, Result="0 B")]
[TestCase(1, Result = "1 B")]
[TestCase(1000, Result = "1 KB")]
[TestCase(1500000, Result = "1.5 MB")]
[TestCase(-1000, Result = "-1 KB")]
[TestCase(int.MaxValue, Result = "2.1 GB")]
[TestCase(int.MinValue, Result = "-2.1 GB")]
[TestCase(long.MaxValue, Result = "9.2 EB")]
[TestCase(long.MinValue, Result = "-9.2 EB")]
public string Format_byte_size(long size)
{
return Format.ByteSize(size);
}
}
Solution 7 - C#
I like to use the following method (it supports up to terabytes, which is enough for most cases, but it can easily be extended):
private string GetSizeString(long length)
{
long B = 0, KB = 1024, MB = KB * 1024, GB = MB * 1024, TB = GB * 1024;
double size = length;
string suffix = nameof(B);
if (length >= TB) {
size = Math.Round((double)length / TB, 2);
suffix = nameof(TB);
}
else if (length >= GB) {
size = Math.Round((double)length / GB, 2);
suffix = nameof(GB);
}
else if (length >= MB) {
size = Math.Round((double)length / MB, 2);
suffix = nameof(MB);
}
else if (length >= KB) {
size = Math.Round((double)length / KB, 2);
suffix = nameof(KB);
}
return $"{size} {suffix}";
}
Please keep in mind that this is written for C# 6.0 (2015), so it might need a little editing for earlier versions.
Solution 8 - C#
int size = new FileInfo( filePath ).Length / 1024;
string humanKBSize = string.Format( "{0} KB", size );
string humanMBSize = string.Format( "{0} MB", size / 1024 );
string humanGBSize = string.Format( "{0} GB", size / 1024 / 1024 );
Solution 9 - C#
Here's a concise answer that determines the unit automatically.
public static string ToBytesCount(this long bytes)
{
int unit = 1024;
string unitStr = "B";
if (bytes < unit)
{
return string.Format("{0} {1}", bytes, unitStr);
}
int exp = (int)(Math.Log(bytes) / Math.Log(unit));
return string.Format("{0:##.##} {1}{2}", bytes / Math.Pow(unit, exp), "KMGTPEZY"[exp - 1], unitStr);
}
"b" is for bit, "B" is for Byte and "KMGTPEZY" are respectively for kilo, mega, giga, tera, peta, exa, zetta and yotta
One can expand it to take ISO/IEC80000 into account:
public static string ToBytesCount(this long bytes, bool isISO = true)
{
int unit = isISO ? 1024 : 1000;
string unitStr = "B";
if (bytes < unit)
{
return string.Format("{0} {1}", bytes, unitStr);
}
int exp = (int)(Math.Log(bytes) / Math.Log(unit));
return string.Format("{0:##.##} {1}{2}{3}", bytes / Math.Pow(unit, exp), "KMGTPEZY"[exp - 1], isISO ? "i" : "", unitStr);
}
Solution 10 - C#
string[] suffixes = { "B", "KB", "MB", "GB", "TB", "PB", "EB", "ZB", "YB" };
int s = 0;
long size = fileInfo.Length;
while (size >= 1024)
{
s++;
size /= 1024;
}
string humanReadable = String.Format("{0} {1}", size, suffixes[s]);
Solution 11 - C#
If you are trying to match the size as shown in Windows Explorer's detail view, this is the code you want:
[DllImport("shlwapi.dll", CharSet = CharSet.Unicode)]
private static extern long StrFormatKBSize(
long qdw,
[MarshalAs(UnmanagedType.LPTStr)] StringBuilder pszBuf,
int cchBuf);
public static string BytesToString(long byteCount)
{
var sb = new StringBuilder(32);
StrFormatKBSize(byteCount, sb, sb.Capacity);
return sb.ToString();
}
This will not only match Explorer exactly but will also provide the strings translated for you and match differences in Windows versions (for example in Win10, K = 1000 vs. previous versions K = 1024).
Solution 12 - C#
There is one open source project which can do that and much more.
7.Bits().ToString(); // 7 b
8.Bits().ToString(); // 1 B
(.5).Kilobytes().Humanize(); // 512 B
(1000).Kilobytes().ToString(); // 1000 KB
(1024).Kilobytes().Humanize(); // 1 MB
(.5).Gigabytes().Humanize(); // 512 MB
(1024).Gigabytes().ToString(); // 1 TB
Solution 13 - C#
Mixture of all solutions :-)
/// <summary>
/// Converts a numeric value into a string that represents the number expressed as a size value in bytes,
/// kilobytes, megabytes, or gigabytes, depending on the size.
/// </summary>
/// <param name="fileSize">The numeric value to be converted.</param>
/// <returns>The converted string.</returns>
public static string FormatByteSize(double fileSize)
{
FileSizeUnit unit = FileSizeUnit.B;
while (fileSize >= 1024 && unit < FileSizeUnit.YB)
{
fileSize = fileSize / 1024;
unit++;
}
return string.Format("{0:0.##} {1}", fileSize, unit);
}
/// <summary>
/// Converts a numeric value into a string that represents the number expressed as a size value in bytes,
/// kilobytes, megabytes, or gigabytes, depending on the size.
/// </summary>
/// <param name="fileInfo"></param>
/// <returns>The converted string.</returns>
public static string FormatByteSize(FileInfo fileInfo)
{
return FormatByteSize(fileInfo.Length);
}
}
public enum FileSizeUnit : byte
{
B,
KB,
MB,
GB,
TB,
PB,
EB,
ZB,
YB
}
Solution 14 - C#
Like @NET3's solution. Use shift instead of division to test the range of bytes, because division takes more CPU cost.
private static readonly string[] UNITS = new string[] { "B", "KB", "MB", "GB", "TB", "PB", "EB" };
public static string FormatSize(ulong bytes)
{
int c = 0;
for (c = 0; c < UNITS.Length; c++)
{
ulong m = (ulong)1 << ((c + 1) * 10);
if (bytes < m)
break;
}
double n = bytes / (double)((ulong)1 << (c * 10));
return string.Format("{0:0.##} {1}", n, UNITS[c]);
}
Solution 15 - C#
I use the Long extension method below to convert to a human readable size string. This method is the C# implementation of the Java solution of this same question posted on Stack Overflow, here.
/// <summary>
/// Convert a byte count into a human readable size string.
/// </summary>
/// <param name="bytes">The byte count.</param>
/// <param name="si">Whether or not to use SI units.</param>
/// <returns>A human readable size string.</returns>
public static string ToHumanReadableByteCount(
this long bytes
, bool si
)
{
var unit = si
? 1000
: 1024;
if (bytes < unit)
{
return $"{bytes} B";
}
var exp = (int) (Math.Log(bytes) / Math.Log(unit));
return $"{bytes / Math.Pow(unit, exp):F2} " +
$"{(si ? "kMGTPE" : "KMGTPE")[exp - 1] + (si ? string.Empty : "i")}B";
}
Solution 16 - C#
I assume you're looking for "1.4 MB" instead of "1468006 bytes"?
I don't think there is a built-in way to do that in .NET. You'll need to just figure out which unit is appropriate, and format it.
Edit: Here's some sample code to do just that:
Solution 17 - C#
How about some recursion:
private static string ReturnSize(double size, string sizeLabel)
{
if (size > 1024)
{
if (sizeLabel.Length == 0)
return ReturnSize(size / 1024, "KB");
else if (sizeLabel == "KB")
return ReturnSize(size / 1024, "MB");
else if (sizeLabel == "MB")
return ReturnSize(size / 1024, "GB");
else if (sizeLabel == "GB")
return ReturnSize(size / 1024, "TB");
else
return ReturnSize(size / 1024, "PB");
}
else
{
if (sizeLabel.Length > 0)
return string.Concat(size.ToString("0.00"), sizeLabel);
else
return string.Concat(size.ToString("0.00"), "Bytes");
}
}
Then you call it:
return ReturnSize(size, string.Empty);
Solution 18 - C#
In order to get the human-readable string exactly as the user's used to in his Windows environment, you should use StrFormatByteSize():
using System.Runtime.InteropServices;
...
private long mFileSize;
[DllImport("Shlwapi.dll", CharSet = CharSet.Auto)]
public static extern int StrFormatByteSize(
long fileSize,
[MarshalAs(UnmanagedType.LPTStr)] StringBuilder buffer,
int bufferSize);
public string HumanReadableFileSize
{
get
{
var sb = new StringBuilder(20);
StrFormatByteSize(mFileSize, sb, 20);
return sb.ToString();
}
}
I found this here: http://csharphelper.com/blog/2014/07/format-file-sizes-in-kb-mb-gb-and-so-forth-in-c/
Solution 19 - C#
My 2 cents:
- The prefix for kilobyte is kB (lowercase K)
- Since these functions are for presentation purposes, one should supply a culture, for example:
string.Format(CultureInfo.CurrentCulture, "{0:0.##} {1}", fileSize, unit); - Depending on the context a kilobyte can be either 1000 or 1024 bytes. The same goes for MB, GB, etc.
Solution 20 - C#
One more approach, for what it's worth. I liked @humbads optimized solution referenced above, so have copied the principle, but I've implemented it a little differently.
I suppose it's debatable as to whether it should be an extension method (since not all longs are necessarily byte sizes), but I like them, and it's somewhere I can find the method when I next need it!
Regarding the units, I don't think I've ever said 'Kibibyte' or 'Mebibyte' in my life, and while I'm skeptical of such enforced rather than evolved standards, I suppose it'll avoid confusion in the long term.
public static class LongExtensions
{
private static readonly long[] numberOfBytesInUnit;
private static readonly Func<long, string>[] bytesToUnitConverters;
static LongExtensions()
{
numberOfBytesInUnit = new long[6]
{
1L << 10, // Bytes in a Kibibyte
1L << 20, // Bytes in a Mebibyte
1L << 30, // Bytes in a Gibibyte
1L << 40, // Bytes in a Tebibyte
1L << 50, // Bytes in a Pebibyte
1L << 60 // Bytes in a Exbibyte
};
// Shift the long (integer) down to 1024 times its number of units, convert to a double (real number),
// then divide to get the final number of units (units will be in the range 1 to 1023.999)
Func<long, int, string> FormatAsProportionOfUnit = (bytes, shift) => (((double)(bytes >> shift)) / 1024).ToString("0.###");
bytesToUnitConverters = new Func<long,string>[7]
{
bytes => bytes.ToString() + " B",
bytes => FormatAsProportionOfUnit(bytes, 0) + " KiB",
bytes => FormatAsProportionOfUnit(bytes, 10) + " MiB",
bytes => FormatAsProportionOfUnit(bytes, 20) + " GiB",
bytes => FormatAsProportionOfUnit(bytes, 30) + " TiB",
bytes => FormatAsProportionOfUnit(bytes, 40) + " PiB",
bytes => FormatAsProportionOfUnit(bytes, 50) + " EiB",
};
}
public static string ToReadableByteSizeString(this long bytes)
{
if (bytes < 0)
return "-" + Math.Abs(bytes).ToReadableByteSizeString();
int counter = 0;
while (counter < numberOfBytesInUnit.Length)
{
if (bytes < numberOfBytesInUnit[counter])
return bytesToUnitConverters[counter](bytes);
counter++;
}
return bytesToUnitConverters[counter](bytes);
}
}
Solution 21 - C#
Here is a method with Log10:
using System;
class Program {
static string NumberFormat(double n) {
var n2 = (int)Math.Log10(n) / 3;
var n3 = n / Math.Pow(1e3, n2);
return String.Format("{0:f3}", n3) + new[]{"", " k", " M", " G"}[n2];
}
static void Main() {
var s = NumberFormat(9012345678);
Console.WriteLine(s == "9.012 G");
}
}
Solution 22 - C#
Here is a BigInteger version of @deepee1's answer that gets around the size limitation of longs (so therefore supports yottabyte and theoretically whatever comes after that):
public static string ToBytesString(this BigInteger byteCount, string format = "N3")
{
string[] suf = { "B", "KiB", "MiB", "GiB", "TiB", "PiB", "EiB", "YiB" };
if (byteCount.IsZero)
{
return $"{0.0.ToString(format)} {suf[0]}";
}
var abs = BigInteger.Abs(byteCount);
var place = Convert.ToInt32(Math.Floor(BigInteger.Log(abs, 1024)));
var pow = Math.Pow(1024, place);
// since we need to do this with integer math, get the quotient and remainder
var quotient = BigInteger.DivRem(abs, new BigInteger(pow), out var remainder);
// convert the remainder to a ratio and add both back together as doubles
var num = byteCount.Sign * (Math.Floor((double)quotient) + ((double)remainder / pow));
return $"{num.ToString(format)} {suf[place]}";
}
Solution 23 - C#
1-liner (plus the prefixes constant)
const String prefixes = " KMGTPEY";
/// <summary> Returns the human-readable file size for an arbitrary, 64-bit file size. </summary>
public static String HumanSize(UInt64 bytes)
=> Enumerable
.Range(0, prefixes.Length)
.Where(i => bytes < 1024U<<(i*10))
.Select(i => $"{(bytes>>(10*i-10))/1024:0.###} {prefixes[i]}B")
.First();
Or, if you want to reduce LINQ object allocations, use for-loop variation of the same:
/// <summary>
/// Returns the human-readable file size for an arbitrary, 64-bit file size.
/// </summary>
public static String HumanSize(UInt64 bytes)
{
const String prefixes = " KMGTPEY";
for (var i = 0; i < prefixes.Length; i++)
if (bytes < 1024U<<(i*10))
return $"{(bytes>>(10*i-10))/1024:0.###} {prefixes[i]}B";
throw new ArgumentOutOfRangeException(nameof(bytes));
}
Solution 24 - C#
This question is old, but a very fast C# function could be:
public static string PrettyPrintBytes(long numBytes)
{
if (numBytes < 1024)
return $"{numBytes} B";
if (numBytes < 1048576)
return $"{numBytes / 1024d:0.##} KB";
if (numBytes < 1073741824)
return $"{numBytes / 1048576d:0.##} MB";
if (numBytes < 1099511627776)
return $"{numBytes / 1073741824d:0.##} GB";
if (numBytes < 1125899906842624)
return $"{numBytes / 1099511627776d:0.##} TB";
if (numBytes < 1152921504606846976)
return $"{numBytes / 1125899906842624d:0.##} PB";
return $"{numBytes / 1152921504606846976d:0.##} EB";
}
This has only one cast and one divide per call and only up to 6 compares. When benchmarking, I found that string interpolation is much faster than using String.Format().