Date Calculator
Add or subtract days, weeks, months or years from any date and see the resulting date and weekday.
Resulting date
2024-02-29
- Day of week
- Thursday
Updates live as you type
Frequently asked questions
Pick a start date, choose “Add”, enter the number of days and select the Days unit. The calculator returns the new date and the weekday it falls on.
There is no 31 February, so the result clamps to the last valid day of the target month — 29 February in a leap year, 28 February otherwise.
Yes. All arithmetic uses calendar-correct logic, so leap days and varying month lengths are accounted for automatically.
This tool works in whole days, weeks, months and years. To add or subtract hours and minutes, use the time calculator instead.
There is no 31 February — here's what happens instead
Start from 31 January 2024 and add 1 month, and the calculator can't return "31 February" because that date doesn't exist — so it clamps to the last valid day of the target month instead. Because 2024 is a leap year, that's 29 February 2024, a Thursday; in a non-leap year, the identical calculation lands on 28 February. This clamping isn't specific to this one example — adding a month to any 29th, 30th or 31st clamps correctly whenever the target month runs shorter, handled automatically every time.
Why one tool covers days, weeks, months and years together
Rather than forcing a mental conversion of "six months" into an approximate number of days, this calculator works natively in whichever unit actually matches the question — days, weeks, months or years — and returns both the resulting date and its weekday. Pick a start date, choose add or subtract, enter an amount and a unit, and the result updates instantly using genuine calendar logic rather than a fixed-day approximation per unit.
Why the weekday isn't just trivia
Project deadlines, contract and notice periods, warranty and return windows, and reminders set weeks or months in advance all benefit from knowing not just the resulting date but which day of the week it falls on — a payment due date or scheduled delivery landing on a weekend can mean it doesn't actually process until the next business day, a detail easy to miss without the weekday shown alongside the date itself.
For the gap between two already-known dates, the days-between-dates calculator is the right tool instead; to add or subtract hours and minutes rather than whole calendar units, the time calculator covers that finer level.