Date Calculator

Add or subtract time from a date

Pick a start date, choose whether to add or subtract, and enter any mix of years, months, weeks, and days. The calculator returns the exact resulting date and the day of the week it falls on — handy for finding a deadline, an anniversary, a renewal date, or "what date is 90 days from now?" without counting on a calendar.

Why month and year math is tricky

Adding days is simple arithmetic, but months and years aren't all the same length, so the tool is calendar-aware. Add one month to January 31 and there's no February 31 — the date clamps to the end of February. Add a year to February 29 in a leap year and you land on February 28. The calculator applies years and months first (handling these edge cases), then adds the weeks and days on top.

Common uses

• Deadlines: 30, 60, or 90 days from an invoice or contract date.
• Renewals & trials: when a subscription, warranty, or free trial ends.
• Milestones: a date a set number of weeks before or after an event.
• Personal: anniversaries, countdowns, or "how old will I be on…" planning.

FAQ

Does it count weekends and holidays?

This tool counts calendar days — every day including weekends. If your deadline only counts working days, use a business-day calculator instead, which skips Saturdays and Sundays.

Can I combine units?

Yes — enter values in several fields at once (for example 1 year, 2 months, and 10 days) and they're all applied together in a single calculation.

Is this date calculator free and private?

Yes, it is free with no sign-up, and the date math runs entirely in your browser. The dates you enter are never uploaded or stored anywhere.

In what order are years, months, and days applied?

The tool applies years and months first, clamping any impossible date such as January 31 plus one month to the end of February, and then adds the weeks and days. Changing the order can occasionally land on a different date, so this fixed sequence keeps results predictable.

Does it handle leap years?

Yes, it is fully calendar-aware, so February 29 in a leap year and the differing lengths of each month are handled automatically. Adding a year to February 29 lands on February 28 in a non-leap year.

Does it work on mobile?

Yes, the calculator is responsive and works on phones and tablets, so you can check a deadline or renewal date on the go.