Add/subtract days
Add or subtract a number of days from a date, and see which day of the week it lands on — for deadlines, return windows, notice periods or a date a set number of days ago.
Result
Result date
Day of the week
How to use this tool
- Enter the starting date.
- Enter how many days to add — use a negative number to subtract.
- Read the resulting date and its day of the week.
Assumptions
- Counts calendar days, not business days — use the business days calculator if you need to skip weekends.
Technical details: what the fields mean
- Start date
startDate - The date to count from.
- Days to add (negative to subtract)
daysToAdd - How many days to add — enter a negative number (e.g. -14) to go backwards instead.
Methodology
Result date = start date + days to add (calendar days, accounting for month/year rollovers).
Worked example
Add one calendar day to 1 Jan 2026
Inputs: Start date: 2026-01-01, Days to add (negative to subtract): 1
Result: 2026-01-02, a Friday — the start date is day zero, not day one
90 days from 12 October 2026
Inputs: Start date: 2026-10-12, Days to add (negative to subtract): 90
Result: 2027-01-10, a Sunday — if the deadline can't fall on a weekend, check whether it moves to the Monday.
Two weeks before 12 October 2026
Inputs: Start date: 2026-10-12, Days to add (negative to subtract): -14
Result: 2026-09-28, a Monday.
A 30-day return window from a 27 November 2026 purchase
Inputs: Start date: 2026-11-27, Days to add (negative to subtract): 30
Result: 2026-12-27, a Sunday. Retailers may count the purchase day as day one, so check their wording.
Practical guidance
- For a working-day deadline (e.g. '10 business days from today'), use the business days calculator instead, since this counts every calendar day.
- Contracts and statutory periods can say whether the first day counts and what happens on a weekend or bank holiday — follow that wording over this calculation.
Common mistakes
- Using this for a business-day deadline (e.g. '5 working days') without accounting for weekends, since this counts every calendar day.
FAQs
Does adding one day count the start date?
No. The entered date is the starting point (day zero); adding 1 advances to the next calendar date. Weekends are included.
What date is 90 days from today?
Enter today's date and 90. From 12 October 2026, for example, it's Sunday 10 January 2027.
How do I count backwards?
Enter a negative number of days, e.g. -14 for two weeks earlier.
Last reviewed: 2026-10-11
Counts calendar days only — for a working-day deadline, use the business days between dates calculator instead.
This tool provides an indicative estimate, based on the assumptions stated above.
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