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Date Calculator

Quick set:

Result

Date math
Difference = end − start (in days) · Result = start ± amount (days/weeks/months/years)

How many days until the wedding? What date is 90 days from today? This date calculator is two tools in one: find the exact days between two dates, or add and subtract days, weeks, months and years from any date — for deadlines, contracts, anniversaries and countdowns.

Days between two dates

Pick a start and end date and the calculator shows the gap in days, weeks-and-days, and years/months/days. The count is exclusive of the start day: from July 1 to July 4 is 3 days (end minus start). Worked example: January 1 to December 25 of the same year is 358 days — about 51 weeks — which is exactly the kind of number you need for savings plans, notice periods or event countdowns.

Adding or subtracting time from a date

Switch to Add/Subtract mode, choose a date, and move forwards or backwards by any amount. "What date is 90 days from March 3?" → June 1. Common uses: 30/60/90-day payment terms, probation periods, warranty windows, medication schedules and project milestones.

How months and leap years are handled

Adding a month lands on the same day-of-month where possible, rolling back when the target month is shorter — January 31 + 1 month gives February 28 (or 29 in a leap year). Leap years are handled automatically throughout, so multi-year spans stay exact.

Related date tools

Counting from a birth date specifically? The age calculator gives an exact age with totals. Need hour-and-minute precision between two timestamps — like shift lengths or travel time? Use the time duration calculator.

Frequently Asked Questions

How do I find the days between two dates? +

Use the "Difference" mode: pick a start and end date and the calculator shows the gap in days, weeks and as years/months/days.

What date is 90 days from today? +

Use the "Add / Subtract" mode with today's date and +90 days — the calculator lands on the exact calendar date, handling month lengths and leap years automatically.

Are both start and end days counted? +

The difference is end minus start — the start day itself is not counted. July 1 to July 4 is 3 days. If you need an inclusive count (both endpoints), add 1.

How does adding months handle short months? +

Adding months lands on the same day-of-month where possible and rolls back when the target month is shorter: January 31 + 1 month gives February 28 (or 29 in a leap year).

How many days until Christmas or another event? +

Set today as the start date and the event as the end date — the difference is your countdown in days and weeks.

Does it account for leap years? +

Yes — all differences and additions use the real calendar, so February 29 and multi-year spans are always exact.

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