Date Add & Subtract Calculator

All tools

Add or subtract years, months, weeks and days from any date to find the resulting date, its weekday, ISO format and how many days it is from today.

Resulting date –
Day of week –
ISO date –
Days from today –
Years and months are added first, then weeks and days. Month-end dates roll over naturally, so adding a month to Jan 31 may land in early March.

About Date Add & Subtract Calculator

The Date Add & Subtract Calculator takes any start date and moves it by a chosen number of years, months, weeks and days — forward or backward. The result shows the new date, its day of the week, its ISO format and how many days it falls from today.

Years and months are applied first, then weeks and days, using real calendar arithmetic. Month-end dates roll over naturally: adding one month to January 31 lands in early March, because February has no 31st. Leap years are handled the same way.

It answers questions like “what date is 90 days from today”, “when does a 6-month notice period end” or “what was the date 3 weeks before the deadline” — without counting on a wall calendar. Free and instant in your browser.

How to use Date Add & Subtract Calculator

  1. Pick the start date (it defaults to today).
  2. Choose the operation: Add or Subtract.
  3. Enter the amounts — years, months, weeks and days, in any combination.
  4. Read the resulting date, its weekday, the ISO date and how many days it is from today.

Frequently asked questions

Years and months first, then weeks and days. This matches how people state durations (“in 1 month and 10 days”) and keeps results predictable when both month and day amounts are involved.

The date rolls over naturally: since February has no 31st day, the result lands in early March (March 2 or 3, depending on leap year). The calculator never silently clips to the month’s last day.

Leave the start date as today, select Add, and enter 90 in the days field. The result shows the exact date, its weekday and its ISO form — useful for probation periods, returns windows and deadlines.

Yes. Switch the operation to Subtract and the same years, months, weeks and days are removed from the start date — handy for working out when something must have started.

The YYYY-MM-DD format defined by ISO 8601, such as 2026-07-03. It is unambiguous across countries and sorts correctly as text, which makes it ideal for documents and filenames.
Share this
Related Tools
Date Difference Calculator Calculate the time between two dates in years, months, days, weeks and hours, or add and subtract durations — with optional business days. Free, in your browser. Free
Age Calculator Find your exact age in years, months and days from a date of birth, plus total months, weeks, days and hours and a countdown to your next birthday. Free
Business Days Calculator Count the working days between two dates, or add a number of business days to a start date, automatically skipping weekends. Free
Time Duration Calculator Calculate the duration between a start and end time in hours and minutes, with totals in minutes, seconds and decimal hours, including overnight spans. Free
Sleep Calculator Find the best times to fall asleep or wake up based on 90-minute sleep cycles, so you wake between cycles feeling refreshed rather than groggy. Free
Online Timer A simple, full-screen countdown timer with quick presets, a custom duration and an alarm when time is up. Free and runs in your browser. Free
Need help?
Found an issue with this tool? Let our team know.
Report an issue

Add this free tool to your own website — copy and paste the code below.