Date Calculator
Add or subtract days from a date — and count the days between two dates.
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Add or subtract days from a date to find a future or past calendar date and the day of the week it lands on — or switch modes to count the exact days between two dates.
Calculations are calendar-correct, accounting for leap years and varying month lengths, and use your local time so there's no timezone drift.
Formula
Add or subtract days
start date ± number of days
Shift a date forward (positive) or backward (negative) by a number of days to get a new calendar date.
Days between dates
|end − start| ÷ 1 day
The difference between two dates, counted in whole days. Weeks, months, and years are derived from the day count.
Examples
| Example | Input | Result |
|---|---|---|
| Add days | Jan 15 2024 + 30 | Feb 14, 2024 |
| Subtract days | Jan 15 2024 − 10 | Jan 5, 2024 |
| Days between | Jan 1 → Dec 31, 2023 | 364 days |
How to use the date calculator
- 1Choose “Add / subtract days” or “Days between dates”.
- 2Pick your start date — then enter a number of days to add (or a negative number to subtract), or pick a second date.
- 3Read the resulting date and weekday (or the day count); copy or share it.
Adding and subtracting days
To find a date a set number of days in the future, add that many days to your start date; to go into the past, subtract. The calculator rolls across month and year boundaries correctly, so adding 30 days to January 15 lands on February 14, and the result shows the day of the week. This is the quickest way to answer questions like “what date is 90 days from today?”.
Counting days between two dates
Switch modes to subtract the earlier date from the later one and count the whole days in between, with the span also shown in approximate weeks, months, and years. For a richer breakdown — including working days versus weekend days — use the Date Difference Calculator; to count down to a single date from today, use the Days Until Calculator.
Leap years and accuracy
Leap years (every four years, with the usual century exceptions) add a day to February, and this calculator accounts for them automatically because it works on real calendar dates. It also uses local-time date handling, so results don't shift by a day across timezones.
Frequently asked questions
How do I add or subtract days from a date?
Choose “Add / subtract days”, pick a start date, and enter the number of days (use a negative number to subtract). The resulting date and weekday are shown — handy for “what date is 90 days from now?”.
What date will it be in a certain number of days?
Enter today as the start date and the number of days to add. The calculator shows the resulting calendar date and which day of the week it falls on.
How many days are between two dates?
Switch to “Days between dates” and pick both dates. This counts the exact whole days and also shows the span in weeks, months, and years. For working-day counts, use the Date Difference Calculator.
Does it account for leap years?
Yes. It works on real calendar dates, so leap years and varying month lengths are handled automatically, with no timezone drift.
Embed this calculator
Add the Date Calculator to your own website — free. Copy and paste this snippet:
<iframe src="https://numvella.com/embed/date-calculator" width="100%" height="460" style="border:1px solid #e2e8f0;border-radius:12px" title="Date Calculator — Numvella" loading="lazy"></iframe>Related calculators
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