Day of the Week: Gregorian calendar; ISO weeks begin on Monday and week 1 contains January 4..
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Day of the Week Calculator for United States
US · 12,345.67US customary measurementsRoad distance: miles
United States display and unit preferences. The stated calculation method is used. Review the labeled units before entering your values.
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Your details
Day of the week
Thursday
United States · calculated from your inputs
Day of year1
ISO week2026-W01
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How this result was calculated
Use the Gregorian calendar's weekday and day-of-year, then compute the ISO week using the week's Thursday.
Country setup: United States. Displayed measurements are converted to the formula's base units internally.
Assumption: Gregorian calendar; ISO weeks begin on Monday and week 1 contains January 4. United States display and unit preferences. The stated calculation method is used. Review the labeled units before entering your values.
Calculation version 1.0.0 · Support state: generic
Formula and method
Use the Gregorian calendar's weekday and day-of-year, then compute the ISO week using the week's Thursday.
This calculation uses the values you enter. It runs in your browser and does not request a location or account.
Worked example
January 1, 2026 is Thursday in ISO week 2026-W01.
Questions people ask
Which method does this tool use?
Use the Gregorian calendar's weekday and day-of-year, then compute the ISO week using the week's Thursday.
What should I check before using the result?
Gregorian calendar; ISO weeks begin on Monday and week 1 contains January 4.