DateTime format string tester

Type a value and a format string to see what DateTime.ToString(format, culture) returns. End the value with Z or an offset to format a DateTimeOffset.

Standard formats

Format	Invariant culture	English (United States)	English (United Kingdom)
d	03/05/2027	3/5/2027	05/03/2027
D	Friday, 05 March 2027	Friday, March 5, 2027	Friday, 5 March 2027
f	Friday, 05 March 2027 14:07	Friday, March 5, 2027 2:07 PM	Friday, 5 March 2027 14:07
F	Friday, 05 March 2027 14:07:09	Friday, March 5, 2027 2:07:09 PM	Friday, 5 March 2027 14:07:09
g	03/05/2027 14:07	3/5/2027 2:07 PM	05/03/2027 14:07
G	03/05/2027 14:07:09	3/5/2027 2:07:09 PM	05/03/2027 14:07:09
M	March 05	March 5	5 March
O	2027-03-05T14:07:09.0456789	2027-03-05T14:07:09.0456789	2027-03-05T14:07:09.0456789
R	Fri, 05 Mar 2027 14:07:09 GMT	Fri, 05 Mar 2027 14:07:09 GMT	Fri, 05 Mar 2027 14:07:09 GMT
s	2027-03-05T14:07:09	2027-03-05T14:07:09	2027-03-05T14:07:09
t	14:07	2:07 PM	14:07
T	14:07:09	2:07:09 PM	14:07:09
u	2027-03-05 14:07:09Z	2027-03-05 14:07:09Z	2027-03-05 14:07:09Z
Y	2027 March	March 2027	March 2027

Common custom formats

Format	Result (invariant)
yyyy-MM-dd	2027-03-05
dd/MM/yyyy	05/03/2027
MM/dd/yyyy	03/05/2027
yyyy-MM-ddTHH:mm:ss.fffffff	2027-03-05T14:07:09.0456789
dddd, MMMM d, yyyy	Friday, March 5, 2027
HH:mm:ss.fff	14:07:09.045
h:mm tt	2:07 PM
yyyyMMddHHmmss	20270305140709
MMM yyyy	Mar 2027

Custom specifiers

d / dd	Day 5 / 05
ddd / dddd	Fri / Friday
M / MM	Month 3 / 03
MMM / MMMM	Mar / March
yy / yyyy	27 / 2027
h / hh	12-hour 2 / 02
H / HH	24-hour 14
m / mm	Minute 7 / 07
s / ss	Second 9 / 09
f … fffffff	Fraction, 1–7 digits
F … FFFFFFF	Fraction without trailing zeros
tt	AM/PM designator
zzz	Offset +10:00 (DateTimeOffset)
K	Offset of a DateTimeOffset (empty for a plain DateTime here)
'text'	Literal text
%d	One-letter custom format

Value used in the tables: 5 March 2027 14:07:09.0456789. Spaces in results are shown as · in the tester.

Formatting durations? Try the TimeSpan format tester.

Questions

Why does "d" give a date but "%d" gives the day?

A format that is a single letter is a standard format (“d” is the short date). Put % in front to use the letter as a custom specifier: “%d” is the day of the month.

Are "/" and ":" literal characters?

“/” and “:” are the culture’s date and time separators, not literal characters. All three cultures here use “/” and “:”. Quote them ('/') to force the literal character.

mm or MM?

mm is minutes, MM is the month. hh is the 12-hour clock and HH the 24-hour clock.

Which .NET version is this checked against?

.NET 10.0.11 on Windows: every format in the tables below and 459 test cases give the same text as ToString in .NET.

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