Days Before Calculator
Subtract Days From a Date
How to Subtract Days From a Date
The days before calculator lets you count backwards from any date. Enter your reference date, the number of days (or weeks/months) to subtract, and get the exact past date. This is useful for finding when a deadline started, backdating documents, or calculating original event dates.
Common Backwards Calculations
| From Date | Subtract | Common Use |
|---|---|---|
| Deadline | 14 days | Find the latest date you could have filed and still met the deadline |
| Today | 90 days | Find when a 90-day probation period started |
| Birth date | 280 days | Estimate conception date (40 weeks pregnancy) |
| Tax deadline | 30 days | Set a reminder 30 days before tax is due |
| Event date | 6 months | Find when planning should have started |
Australian Context
- Fair Work deadlines — Unfair dismissal applications must be lodged within 21 days. Count backwards from the deadline to find the dismissal date
- Warranty claims — Subtract the warranty period from today to check if the purchase is still covered
- Centrelink payments — Track back 14 days to find the start of a payment period
- Insurance claims — Many policies require lodgement within 30 or 60 days of an event
Need to Add Days Instead?
Use our forward date calculator to find future dates.
Forward Date CalculatorFrequently Asked Questions
How do I subtract days from a date?
Enter the reference date in the calculator above, type the number of days to subtract, and click Calculate. The result shows the exact past date.
Can I subtract months from a date?
Yes. Select 'Months' from the dropdown to subtract calendar months. The calculator handles edge cases like month-end dates.
Does this calculator account for leap years?
Yes, the calculator uses JavaScript's native date handling which correctly accounts for leap years and varying month lengths.