Start from a date, choose add or subtract, and enter days, weeks or months to get the resulting date — shown with its weekday. Handy for deadlines, delivery windows, notice periods and “90 days from now” questions. It all runs on your device.
Pick a start date and enter how much to add or subtract.
Months are clamped to the end of the month; days and weeks count every calendar day, weekends included.
How it works
Days and weeks are added as flat 24-hour calendar days, computed via UTC midnights so daylight-saving changes never shift the result by a day. Months are applied first and clamped to the end of the month, so 31 January minus one month lands on the last valid day rather than rolling into the wrong month.
You can combine all three fields in one calculation — for example add 2 months, 1 week and 3 days at once. The result shows the full weekday and date, plus the plain YYYY-MM-DD form you can copy straight into a form or spreadsheet.
Practical examples
90 days from a date
A payment due “90 days” after 2026-01-15 lands on 2026-04-15. Enter the date, keep “add”, and put 90 in the days field.
Two weeks’ notice
Handing in notice on 2026-03-02? Add 2 weeks to see the last working date — 2026-03-16, a Monday — so there’s no counting on fingers.
Month-end that behaves
Subtract 1 month from 2024-03-31 and you get 2024-02-29 (a leap year), not a date that spills into the wrong month. The tool clamps to the real month end.
Frequently asked questions
How are months handled at the end of a month?
They’re clamped. Adding one month to 31 January gives 28 February (or 29 in a leap year), because February has no 31st. This matches how banks and contracts treat monthly dates and avoids landing in March by accident.
Can I add days, weeks and months together?
Yes. Fill in any combination and they’re applied in one step — months first (clamped), then the flat days from the day and week fields. Leave a field blank or at zero to skip it.
Does it count weekends and holidays?
It counts every calendar day, weekends included. It doesn’t skip public holidays; a working-days calculator that knows Serbian holidays is a separate, planned tool.
Why show the weekday of the result?
Most “add days” questions are really about landing on a workday — a due date or delivery slot. Seeing that the result is, say, a Sunday lets you adjust before it becomes a problem.
Are leap years taken into account?
Yes. Day and week math counts real calendar days, so spans crossing 29 February include it, and month clamping produces 29 February in leap years where appropriate.
Can the result go into the past or far future?
Yes. Subtracting more days than have elapsed moves into the past, and large values move far into the future. Each field accepts whole numbers up to a million, which covers any realistic planning range.
Why is the date also shown as YYYY-MM-DD?
That ISO format is unambiguous and pastes cleanly into spreadsheets, forms and code. The long weekday-and-month line above it is for reading; the ISO line is for copying.
Is the date I enter kept private?
Yes. The calculation runs entirely in your browser; nothing is uploaded and analytics never receives the date.
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