What date is 90 days from today? When does a 45-day return window end? What was the date six weeks ago? These are everyday questions for contracts, medicine courses, warranties and visas. This guide explains how to add or subtract days from a date correctly, and how our free Date Calculator (Add or Subtract Days) does it instantly, including business days.
Adding days by hand
- Start from the date.
- Subtract the days left in the current month from the number you are adding.
- Move month by month until the remaining days fit inside a month.
Example: 90 days after 10 October 2026
| Step | Days used | Remaining |
|---|---|---|
| Rest of October (11–31) | 21 | 69 |
| November | 30 | 39 |
| December | 31 | 8 |
| January | 8 | 0 |
Result: 8 January 2027, a Friday.
Quick reference from 10 October 2026
| Add | Date |
|---|---|
| 7 days | 17 October 2026 |
| 30 days | 9 November 2026 |
| 60 days | 9 December 2026 |
| 90 days | 8 January 2027 |
| 180 days | 8 April 2027 |
Subtracting days
Work backwards the same way. 45 days before 10 October 2026 is 26 August 2026.
Adding months instead of days
“Three months from 31 January” ends on 30 April, because the calculator keeps the same day where possible and uses the last day of shorter months. Months and days are not interchangeable: 3 months can be 89 to 92 days.
Business days
Adding 10 business days skips weekends: from a Thursday, 10 business days later is the Thursday two weeks on. Public holidays are not skipped automatically, so check Pakistan Public Holidays and add a day for each one.
Where this is useful
- Payment terms on invoices (Net 30) with the Invoice Generator
- Return and warranty periods
- Medicine courses and follow-up visits
- Notice periods and visa deadlines; read counting days for visas and contracts
For the reverse question, how many days between two dates, read business days explained or use the Date Difference Calculator.
Frequently asked questions
What date is 90 days from today?
Enter today in the date calculator and add 90 days; it also shows the weekday.
Does adding a month always add 30 days?
No. It moves to the same day next month, which can be 28 to 31 days later.
Are public holidays skipped in business days?
Only weekends are skipped automatically.