Counting back from a date
Subtracting days is the reverse of adding them: the calculator moves back the given number of calendar days, across month and year boundaries, and gives you the earlier date. With Business days selected, it counts back only Monday-to-Friday days (and can skip US federal holidays), which is how many “X working days before” deadlines are calculated.
Earlier date = start date − number of days
Common “days ago” dates
Calculated from today:
| Period | Date |
|---|---|
| 7 days ago | |
| 14 days ago | |
| 30 days ago | |
| 60 days ago | |
| 90 days ago | |
| 100 days ago | |
| 180 days ago | |
| 365 days ago |
When you need to subtract days
- Look-back periods: “in the last 90 days”, “within 30 days of purchase”.
- Back-scheduling: if a project must finish on a date and takes 45 days, when must it start?
- Notice periods: the last day to give 30 days’ notice before a date.
- Pregnancy: the conception date is about 266 days before a due date — see the Reverse Due Date Calculator.
To find the number of days between two dates instead, use Days Between Dates; to go forward, use Add Days to Date.