Use this free online date calculator to add or subtract years, months, and days from any starting date. Instantly find a future or past date along with its day of the week - ideal for planning deadlines, anniversaries, or scheduling events.
How to Use the Date Calculator
- Pick your starting date using the "Start Date" field.
- Choose whether to Add or Subtract time from the Operation dropdown.
- Enter the number of Years, Months, and/or Days to apply.
- Click "Calculate" to see the resulting date and its day of the week.
- Use "Clear" to reset all fields and start a new calculation.
How the New Date Is Worked Out
Years and months do not have a fixed number of days, so the calculator does not convert everything into days. It moves along the calendar in two stages:
- Years and months are applied first. Each year counts as 12 months, and the date moves to the same day number in the target month. If that day does not exist there, for example 31 January plus 1 month, the last day of the target month is used, giving 28 February (or 29 February in a leap year).
- Days are then added or subtracted one calendar day at a time, rolling over month and year ends as a wall calendar would.
"1 month" and "30 days" are not the same thing. 31 January 2026 plus 1 month is 28 February 2026, but 31 January 2026 plus 30 days is 2 March 2026. Use months when a rule is stated in months, and days when it is stated in days.
Worked Examples
Results for a start date of 2 October 2026 (a Friday):
| Operation | Result date | Day |
|---|
| Add 30 days | 1 November 2026 | Sunday |
| Add 45 days | 16 November 2026 | Monday |
| Add 90 days | 31 December 2026 | Thursday |
| Add 6 months | 2 April 2027 | Friday |
| Add 444 days | 20 December 2027 | Monday |
| Add 1 year, 2 months, 10 days | 12 December 2027 | Sunday |
| Subtract 100 days | 24 June 2026 | Wednesday |
Everyday Uses in India
- Fixed deposit maturity: banks often offer tenures stated in days, such as 400 or 444 days. Add the tenure in days to the deposit date to see when it matures.
- Cheque validity: a cheque is generally valid for three months from the date written on it. Add 3 months to the cheque date to see the last date to deposit it.
- Notice periods and probation: add 30, 60 or 90 days (or the number of months in your appointment letter) to your resignation or joining date.
- Return, warranty and subscription windows: add the stated days or months to the purchase or activation date.
- Going backwards: subtract days to find when you must start, for example the last date to post documents that need 15 days to arrive.
Inclusive or Exclusive Counting
The calculator counts the way a calendar does: "add 1 day" to Monday gives Tuesday, so the start date itself is day 0. Some rules count the start date as day 1, so "within 90 days of 2 October" may end on 30 December rather than 31 December. When a deadline matters legally or financially, check how the authority, bank or contract counts the days and adjust by one if needed.
Bank holidays and weekends are not skipped. If a due date falls on a Sunday or a holiday, many payments and filings move to the next working day, but this varies, so confirm with the organisation involved. To count only working days, use the Working Days Calculator.
Frequently Asked Questions
It applies the years and months first, then the days. Extra days roll into the next month or year the same way a calendar would, so adding 45 days to 2 October gives 16 November. If the start day does not exist in the target month, such as 31 January plus 1 month, it uses the last day of that month.
Yes. Select "Subtract" as the operation and enter any combination of years, months, and days - all of them will be deducted from the start date together.
The next year usually has no 29 February, so the calculator gives 28 February. Adding four years from a leap day lands on 29 February again, as long as that year is a leap year.
No. Every calendar day is counted. For deadlines that count only working days, use the Working Days Calculator, and check whether your organisation follows a different holiday list.
This tool moves a date forward or backward by a given amount. To measure the gap between two known dates, use the Date Difference Calculator instead.