Wyvek

Date Calculator

Add or subtract days from a date.

Operation

Choose a start date and an amount to see the resulting date.

Free online date calculator

This date calculator adds or subtracts years, months, weeks, and days from any starting date and instantly shows the resulting date, the day of the week, and the plain yyyy-mm-dd value. It answers everyday questions like "what date is 90 days from today?", "when is 6 weeks before this deadline?", or "what will the date be one year and three months from now?". It's ideal for project deadlines, notice periods, contract and warranty end dates, due dates, and countdowns. Everything runs in your browser, so your dates stay completely private.

How to add or subtract dates

  1. Pick your Start date — it defaults to today.
  2. Choose Add or Subtract for the direction.
  3. Enter any mix of Years, Months, Weeks, and Days — blank fields count as zero.
  4. Read the resulting date and weekday as the result updates live.
  5. Click Copy result to drop the date into a form, email, or calendar.

How the calculation works

The years and months are combined and applied first, then the weeks and days. Month and year changes clamp to the final valid day of the target month, so 31 January plus one month becomes the end of February. Leap years are handled automatically. The start date is read as a calendar date, which means the result never slips by a day because of your timezone. Need the gap between two known dates instead? Use the date difference calculator. Working out someone's age from a birthday? Try the age calculator.

Private and instant

There is no sign-up and nothing is uploaded — the maths happens locally on your device. Bookmark this page the next time you need to add or subtract days from a date in a hurry.

Frequently asked questions

How does the date calculator work?

Pick a start date, choose whether to add or subtract, then enter any mix of years, months, weeks, and days. The tool applies the offset and shows the resulting date, its weekday, and the plain yyyy-mm-dd value — all instantly in your browser as you type.

How are months and years handled when they overflow?

Months and years are applied first and clamp to the last valid day of the target month, then weeks and days are applied. For example, adding one month to 31 January gives 28 February, or 29 February in a leap year.

In what order are the values applied?

Years and months are combined and applied together first, then weeks and days are combined and applied. This matches how people usually think about date offsets and keeps results predictable when a field pushes past the end of a month.

Can I leave a field blank?

Yes. Any empty field is treated as zero, so you can add just days, just months, or any combination. Leave the fields you do not need untouched and only fill in the amounts that matter.

Are my dates kept private?

Yes. This date calculator runs entirely in your browser using JavaScript. The date and amounts you enter are never uploaded, stored, or shared, so it is safe for private planning and sensitive deadlines.

Does it avoid timezone problems?

It does. Date-only calculations use UTC calendar-day arithmetic rather than elapsed local hours, so daylight saving changes cannot shift the result or lose a day.

Unix Timestamp Converter Convert Unix timestamps to dates and back. Date Difference Calculator Count days, weeks & months between dates. Time Zone Converter Convert times between time zones.