Add or Subtract Days

Pick a start date, then add or subtract years, months, weeks, or days. The result includes the weekday of the new date.

Runs in your browser — dates never leave this device

Age will show up here Enter a date of birth. You can change the “age at” date if you want a day other than today.

How to use it

1
Enter the start date.
2
Fill in any combination of years, months, weeks, and days. Use a minus sign to subtract.
3
Read the resulting date and the day of the week.

How this calculator counts age

Years and months are applied first, keeping the same day of the month when it exists. 31 January plus one month becomes 28 February in a common year, or 29 February in a leap year. Weeks and days are then added as calendar days.

The weekday is taken from that civil date. Time of day and daylight saving are not used.

Other date tools

Age calculatorExact age in years, months, and days Chronological age calculatorAge on an assessment date, with Y;M;D copy Baby age calculatorWeeks, calendar months, and days after birth Dog age calculatorA size-based estimate in human years Cat age calculatorAn estimate in human years from a public chart Days between datesCount days, with or without the end date Day of the week calculatorWeekday, day of year, and ISO week

Questions

What happens if I add a month to 31 January?

February does not have 31 days, so the result is the last day of February.

Can I add 90 days?

Yes. Put 90 in the days field, or 12 weeks and 6 days — both land on the same date.

How is this different from “days between dates”?

This page starts with one date and a distance. The other page starts with two dates and tells you the distance. They are linked to each other.