What date is 90 days from today? When was 6 months ago? When is the deadline if you have 10 business days? Enter a start date and how much to add or subtract to get the answer instantly.
What you can add
- Calendar days – every day counts.
- Business days – Monday to Friday only (public holidays not excluded).
- Weeks – 7 days each.
- Months and years – keeps the same day of the month. If that day doesn’t exist (31 Jan + 1 month), it moves to the last day of the month (28 or 29 Feb).
Common date offsets
| Offset | Often used for |
|---|---|
| 30 days | Return windows, notice periods, invoice terms (Net 30) |
| 45 / 60 days | Payment terms, warranty claims |
| 90 days | Probation periods, visa stays, notice periods |
| 180 days | Visa and residency rules, medical follow-ups |
| 280 days (40 weeks) | Estimated due date from the first day of the last period |
Tips
- For legal deadlines, check whether the start day counts – the calculator doesn’t count the start date when adding.
- The ISO week number shown is handy for project plans in Europe.
Dates from 22 October 2026 (reference)
| Add | Date |
|---|---|
| 30 days | Saturday, 21 November 2026 |
| 45 days | Sunday, 6 December 2026 |
| 60 days | Monday, 21 December 2026 |
| 90 days | Wednesday, 20 January 2027 |
| 120 days | Friday, 19 February 2027 |
| 180 days | Tuesday, 20 April 2027 |
| 6 months | Thursday, 22 April 2027 |
| 1 year | Friday, 22 October 2027 |
Notice that 180 days and 6 months are not the same – months have different lengths.
Business-day deadlines
Contracts, banks and courts often set deadlines in business days. Ten business days from a Monday usually lands on the Friday of the following week. Remember to skip public holidays manually, since they differ by country and state.
Practical uses
- Returns and refunds: find the last day of a 30-day return window.
- Medicine and plans: when a 90-day supply runs out.
- Travel: the latest exit date for a 90-day visa or Schengen-style stay (check the official rules for how days are counted).
- Payments: Net 30, Net 45 or Net 60 invoice due dates.
- Pregnancy: an estimated due date is 280 days from the first day of the last menstrual period.
- Fitness and habits: the end date of a 75-day or 100-day challenge.
Spreadsheet formulas
In Excel or Google Sheets: =A1+90 adds 90 calendar days, =WORKDAY(A1,10) adds 10 business days, and =EDATE(A1,6) adds 6 months.
Real-life scenarios
- Online shopping: Sarah bought a laptop on 22 October with a 30-day return window. Adding 30 days shows the last day to return it is 21 November.
- Freelance invoices: An invoice dated 5 January on Net 45 terms is due 45 days later, on 19 February.
- Probation periods: Rahul joined on 1 July with a 6-month probation. Adding 6 months gives 1 January as the date his confirmation is due.
- Medication refills: A 90-day prescription filled on 15 March runs out on 13 June – set a reminder a week earlier.
- Legal and admin deadlines: A form must be returned within 10 business days of a letter dated Thursday 8 October; skipping weekends gives Thursday 22 October.
Calendar days vs business days
Calendar days count every day, including weekends and holidays. Business days skip Saturdays and Sundays. A “14-day” deadline is very different from “14 business days” – the second is usually close to three weeks. Read the wording carefully, especially on contracts, visas and refund policies.
Related calculators
- Days between dates – count days between two dates
- Age calculator – exact age as on any date
- Notice period calculator – last working day
FAQs
What date was 100 days ago?
Choose “Subtract”, enter 100 and leave the start date as today.
Does adding one month to 31 January give 3 March?
No. The calculator keeps you in February and returns the last day of February (28th or 29th), which is how most banks and contracts treat it.
How do I find a date in the past?
Choose “Subtract”. For example, subtract 18 years from today to find the latest birth date for someone who is 18.
Can I work out my notice period end date?
Yes, but the notice period calculator handles buyouts and the resignation-day rule for you.