# Date add and subtract calculator

Add or subtract days, weeks, months or years from a date

Use it at https://www.quicktoolz.com/tools/date-add-subtract. From QuickToolz.

To find a future or past date, pick a start date and add or subtract any number of days, weeks, months or years. Adding one month to 31 January gives the last day of February, because February has no 31st. The result shows the date and the day of the week.

## How it works

new date = start date ± amount

Days and weeks are exact counts. Months and years move along the calendar, so the day stays the same where it can.

If that day doesn’t exist in the new month, we use the month’s last day and say so.

Worked example: 31 Jan 2026 plus 1 month is 28 Feb 2026, because February has no 31st. We use the last day of the month instead.

## Examples

| From 31 Jan 2026 | Result |
| --- | --- |
| Plus 30 days | 02 Mar 2026, Monday |
| Plus 6 weeks | 14 Mar 2026, Saturday |
| Plus 1 month | 28 Feb 2026, Saturday |
| Minus 1 year | 31 Jan 2025, Friday |

## What this tool doesn't cover

- This doesn’t skip weekends or holidays.

## Questions

### What is 31 January plus one month?

It’s 28 February, or 29 February in a leap year.

### Is 90 days the same as 3 months?

No. Months have different lengths, so choose the one your contract or deadline uses.

### Can I count backwards?

Yes. Choose Subtract.

### How do I find the date 30 days from today?

Choose today as the start date, then add 30 days. The tool crosses month and year ends for you.

### How do I work out a deadline from a notice period?

Enter the start date and add the days or months in your notice period. Check your contract, because some count only working days.

## Sources

- [ISO 8601 date and time format](https://www.iso.org/iso-8601-date-and-time-format.html)