Add Days to a Date Calculator
Start with a date and add or subtract any number of days, weeks, months or years to find the resulting date.
Your numbers
How we calculate it
Days and weeks are added as exact 24-hour calendar days. Months and years move the calendar month while keeping the day number; if the target month is shorter, the date is clamped to the month’s last day, so January 31 plus one month is February 28 (or 29).
The weekday is shown so you can plan around weekends.
Assumptions and limits
- Business days and public holidays are not skipped.
- Months and years are rounded to whole numbers.
Frequently asked questions
What is 90 days from today?
Choose today as the start, 90 as the amount and days as the unit. The tool shows the date and its weekday.
Why is one month from January 31 not March 3?
Calendar months have different lengths, so the standard approach is to land on the last valid day of the shorter month, which is February 28 or 29.
Can I count backward?
Yes. Switch the operation to subtract.
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Worked example (a fixed example using the starting numbers, it does not change as you type)
Inputs: Starting date = March 15, 2026; Operation = Add; Amount = 90; Unit = Days.
- Resulting date Saturday, June 13, 2026
- ISO format 2026-06-13
- Days from start 90
Embed this calculator
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