Add or Subtract Days from a Date

Start from any date, add or subtract days, working days, weeks, months or years, and get the resulting date with its day of the week.

Dates from today

Everyday examples

The 14-day cancellation period

When you buy online, the Consumer Contracts Regulations 2013 usually give you 14 days to change your mind. For goods, the period ends 14 days after the day you receive them: a parcel delivered on Thursday 8 October 2026 can be cancelled until Thursday 22 October 2026. For services, it runs from the day after the contract is made.

Invoice payment terms

To find the due date of an invoice payable in 30 days, add 30 days to the invoice date. Between businesses, when no payment date has been agreed, late payment interest can be claimed after 30 days; payment terms longer than 60 days must be expressly agreed and not grossly unfair to the supplier.

Periods expressed in months

In UK legislation, a “month” means a calendar month. A period of months ends on the corresponding date in the final month; if that month is too short, it ends on its last day. The calculator follows exactly this rule with the “Months” and “Years” units. The details of a legal deadline depend on the rule that sets it, so check it when it matters.

Frequently asked questions

Is the start day counted?

No. Adding 1 day gives the next day, and adding 7 days gives the same weekday a week later. If the start day should count, subtract 1 from the number of days.

How do I find a date in the past?

Choose “Subtract”. You can also enter a negative number: −30 with “Add” is the same as subtracting 30 days.

What date will it be in 100 days?

The “Dates from today” table answers this for the most common periods, including 7, 30, 60, 90, 100, 180 and 365 days. It is recalculated every day.

Are bank holidays taken into account?

Only with the “Working days” unit, which skips weekends and bank holidays in England and Wales. With calendar days, the calculator tells you when the resulting date falls on a weekend or a bank holiday.

Can I enter large numbers?

Yes, with or without a thousands separator: “1000” and “1,000” give the same result. The number must be a whole number.

How to add days to a date

Adding days means moving forward that many squares on the calendar: adding 1 day takes you to the next day, and the start day itself is not counted. By hand, go month by month:

1. Work out the days left in the start month and subtract them from the number to add.
2. Subtract the length of each full month as long as what remains is greater than the next month.
3. What remains is the day number in the month you have reached.

Example: 8 October 2026 plus 90 days. October has 23 days left (67 remaining), November uses 30 (37 remaining) and December 31 (6 remaining). You land on 6 January 2027, a Wednesday. To subtract, do the same thing backwards.

Adding weeks, months or years

A week always has 7 days, so adding weeks keeps the same weekday: a Thursday plus 3 weeks is still a Thursday.

Months need more care because they vary in length. The calculator keeps the same day of the month: 8 October plus 2 months is 8 December. If that day does not exist, it uses the last day of the month: 31 January 2027 plus 1 month is 28 February 2027. The same rule applies to years and only matters for 29 February: 29 February 2028 plus 1 year is 28 February 2029.

Adding working days

With the “Working days” unit, only Mondays to Fridays that are not bank holidays count. Example: Friday 18 December 2026 plus 5 working days. The calculator counts Monday 21, Tuesday 22, Wednesday 23 and Thursday 24 December, skips Christmas Day (Friday 25), the weekend and the Boxing Day substitute day (Monday 28), so the fifth working day is Tuesday 29 December 2026.

More date calculators

• Days between datesDifference in days, weeks, months and years, with working days.
• Working daysMonday to Friday, with bank holidays in England and Wales excluded.
• Age calculatorExact age in years, months and days, plus your 10,000th day.
• Week numberThe ISO week number of any date and the full week calendar.
• CountdownHow many days until Christmas, Easter or any date you choose.