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 CalculatorExternal Resources
- Canstar — Australian financial comparison and planning tools
- Fair Work Ombudsman — Australian employment law, notice periods, and leave entitlements
- Employment Hero — Australian HR and payroll platform
- SEEK — Australian employment and career resources
Frequently 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.