Render Unicode or strftime date patterns against a chosen UTC date and time; inspect ISO week-year, ordinal day, token references, common formats and New Year mistakes.
DATE, TIME & TIMEZONE · LOCAL WORKBENCH · BROWSER WORKSPACE
Test your date pattern. Catch the New Year bug before it ships.
Render Unicode or strftime date patterns against a chosen UTC date and time; inspect ISO week-year, ordinal day, token references, common formats and New Year mistakes.
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01 · TEST THE PATTERNUTC · EXPLICIT INPUT
TRY A KNOWN FORMATLOAD PATTERN
Pattern tokens are not interchangeable.Unicode: MM means month, mm means minutes; yyyy is calendar year and YYYY is ISO week-year. strftime: %m is month and %M is minutes.
02 · RENDERED RESULTUNICODE TOKENS
RENDERS AS · UTC2020-12-365 14:05:09
Pattern reviewYour pattern uses Y, the ISO week-numbering year. For this date the calendar year is 2019, while the week year is 2020; the rendered value is 2020-12-365 14:05:09. Use lowercase yyyy unless you deliberately need a week-year.
CALENDAR YEAR2019ISO WEEK-YEAR2020week W01DAY OF YEAR365of 365
03 · COMMON FORMATS, SAME MOMENT9 EXAMPLES
ISO dateyyyy-MM-dd2019-12-31ISO 8601 in UTCyyyy-MM-dd'T'HH:mm:ss'Z'2019-12-31T14:05:09Zday first — most of the worlddd/MM/yyyy31/12/2019month first — ambiguous with the line aboveMM/dd/yyyy12/31/2019long formEEEE d MMMM yyyyTuesday 31 December 2019ordinal dateyyyy-DDD2019-365ISO week dateyyyy-'W'ww-e2019-W01-e24-hour timeHH:mm14:0512-hour timehh:mm a02:05 PM
04 · TOKEN REFERENCE17 TOKENS
yyyy2019calendar year · usually preferredyy19two-digit calendar yearYYYY2020ISO week-numbering year — not the calendar yearMM12month, two digits · usually preferredMMMDecmonth, short nameMMMMDecembermonth, full namedd31day of the month · usually preferredDDD365day of the yearEEETueweekday, shortEEEETuesdayweekday, fullHH14hour, 24-clock · usually preferredhh02hour, 12-clockmm05minutes · usually preferredss09seconds · usually preferredaPMAM or PMww01ISO week number'T'Ta literal T — quotes make it literal
Timezone and runtime limits
All values are interpreted as UTC so the sample is repeatable. This is a focused token tester, not a full implementation of every ICU, Java, .NET, Moment or platform-specific date token. Unknown tokens stay literal. Use the target library to confirm compatibility before shipping.
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Runs in this browser. Results are estimates or editing cues. Review the assumptions and source-specific limits before using them in a consequential decision.
Render Unicode or strftime date patterns against a chosen UTC date and time; inspect ISO week-year, ordinal day, token references, common formats and New Year mistakes. Results update as you adjust inputs and stay in this browser.
