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Add or Subtract Days Calculator

Add or subtract a number of days from a date to find the result.

Result date

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What this calculator does

This online add or subtract days calculator adds or subtracts a specific number of days from a starting date, showing the exact resulting date and its day of the week. It's the quickest way to answer "what date is 45 days from now?" or "what date was 60 days ago?" without counting manually.

Worked example

Starting from September 2, 2026 and adding 100 days lands onDecember 11, 2026, a Friday.

Common mistakes

  • Treating "days" and "business days" the same. This calculator counts every calendar day, including weekends — use the business days calculator if you need workdays only.
  • Off-by-one counting. Manually counting on a calendar is easy to get wrong across month boundaries — automated calculation avoids that.
  • Forgetting leap years. A date range spanning February 29 in a leap year shifts the result by one day compared to a non-leap year.

Frequently asked questions

How do I add or subtract days from a date?+

Enter your starting date, choose add or subtract, and enter the number of days — the calculator instantly shows the resulting date and its day of the week. Adding days is a fixed count regardless of month length: adding 30 days to January 1 lands on January 31, while adding 1 month instead would land on February 1 — the two aren't interchangeable, even though a month averages around 30 days.

Can I subtract days to find a past date?+

Yes — switch to "subtract" to count backward from your starting date by any number of days.

Does this tool tell me the day of the week for the result?+

Yes — the result includes the full weekday name so you can immediately see whether it falls on a weekday or weekend.

What's the difference between this and the general date calculator?+

This tool is focused specifically on adding or subtracting a number of days. The general date calculator also supports weeks, months, and years if you need those units instead.

Related calculators

Leap Year CheckerCheck instantly whether a year is a leap year. Days Between Two Dates CalculatorFind the exact number of days between two dates. Date CalculatorAdd or subtract days, weeks, months, or years from a date. Date Duration CalculatorFind the duration between two dates in years, months, and days.