String formatting in .NET C# is easy – the hard part is looking up what all the formatting specifiers do. I find myself constantly checking the (rather wordy) .NET documentation just to format a date or a currency value. This cheat sheet brings all the String.Format formatting specifiers together in one easy overview.

How to format

The String.Format method is your friend. It can format any number of arguments into a string, like so:

String.Format("{0} and {1} is {2}", 2, 2, 2+2)

which returns

2 and 2 is 4

Wherever you want String.Format to insert a formatted value, place curly braces containing the index of the argument (0 being the first argument, 1 being the second and so on). The String.Format method will format your arguments according to its default formatting rules (depending on the argument types) and place them in the result string. But what if you want your values formatted in a special way? You use formatting specifiers like so:

String.Format("{0:c}", 3.456)



In other words, you place a colon and a formatting specifier after the argument index.

Formatting Numbers

Standard Numeric Format Strings

SpecifierTypeFormatSample (36.45)Sample (-12345)
n/NNumber with thousand separator{0:n}36.45-12,345.00
p/PPercentage{0:0}3,645.00 %1,234,500.00 %
  • Round-trip formatting is converting a number to a string in such a way that it can be converted back into the same number. This conversion is only supported for single and double types.
  • Currency conversion will use the currency symbol, thousands and decimal separators specified by the current Culture.
  • Percentage conversion multiplies the number by 100, then adds a percentage sign.


Each number formatting specifier can be accompanied by a precision (if omitted, the default precision is assumed):

SpecifierTypeFormatPrecision specifier functionDefault precisionSample (precision 6)Result
c/CCurrency{0:c6}Number of decimal digitsDefined by System.Globalization.NumberFormatInfo3.45$3.450000
d/DDecimal{0:d6}Minimum number of digitsMinimum number of digits required123000123
e/EScientific{0:e6}Number of decimal digits63.453.450000e+000
f/FFixed-point{0:f6}Number of decimal digitsDefined by System.Globalization.NumberFormatInfo3.453.450000
g/GGeneral{0:g6}Number of significant digitsDepends on numeric type3.353.45
n/NNumber with thousand separator{0:n6}Desired number of decimal placesDefined by System.Globalization.NumberFormatInfo3.453.450000
p/PPercentage{0:p6}Desired number of decimal placesDefined by System.Globalization.NumberFormatInfo0.34534.500000 %
r/RRound-trip{0:r6}Ignored 3.453.45
x/XHexadecimal{0:x6}Number of digits in the result string 345000159

Custom Number Formatting

Beyond the standard numeric format strings, you can define your own specific formatting. You can mix and match the following:

0Zero placeholder{0:0000.0000}3.4500003.4500
#Digit placeholder{0:#####:##}531.456531.45
.Decimal separator{0:0,000.00}1234.451,234.45
,Thousands separator{0:0,000.00}1234.451,234.45
%Percent sign{0:0.00%}0.4545.00%
  • The zero placeholder allows you to pad a number with zeroes.
  • The percent sign multiplies a value by 100, then adds a percent sign.

Formatting Dates

dShort date08/03/2013
DLong dateFriday, March 08, 2013
fFull date and time, shortFriday, March 08, 2013 10:10 AM
FFull date and time, longFriday, March 08, 2013 10:10:44
gDefault date and time08/03/2013 10:10 AM
MMonth and dayMarch 08
rRFC1123 dateFri, 08 Mar 2013 10:10:44 GMT
sSortable date string2013-03-08T10:10:44
tShort time10:10 AM
TLong time10:10:44
uUniversal sortable local time2013-03-08 10:10:44Z
UUniversal GMTFriday, March 08, 2013 08:10:44
YMonth and yearMarch, 2013

Custom Date Formatting

dDay, zero-padded{0:dd}08
ddd3-letter day name{0:ddd}Fri
ddddFull day name{0:dddd}Friday
ffSecond fractions, 2 digits{0:ff}19
fffSecond fractions, 3 digits{0:fff}193
ffffSecond fractions, 4 digits{0:ffff}1934
hhHour (2 digits, 12H){0:hh}10
HHHour (2 digits, 24H){0:HH}10
mmMinutes, zero-padded{0:mm}16
MMMonth, zero-padded{0:MM}03
MMM3-letter month name{0:MMM}Mar
MMMMFull month name{0:MMMM}March
yy2-digit year{0:yy}13
yyyy4-digit year{0:yyyy}2013
zz2-digit timezone offset{0:zz}+02
zzzFull timezone offset{0:zzz}+02:00


You can now place various custom date formatting specifiers in a formatting string like so:

String.Format("{0:hh:mm tt, ddd-MM-MMM yyyy gg}", DateTime.Now)

which yields

10:26 AM, Fri-03-Mar 2013 A.D.