Date Calculator

Find the date a number of days from another, or count the days between two dates.

This tool runs entirely in your browser. Your data is never uploaded, never stored, and never leaves your device.

This answers the two date questions people actually ask — what date is 30 days from now, and how many days lie between two dates — in calendar days or in business days that skip weekends.

How to use it

1Choose whether you are moving forward from a date or counting between two.
2Set the starting date; it opens on today.
3Pick days, business days, weeks, months or years, and whether to go forwards or back.

Example

Input: 30 days after 1 March 2026
Output: Tuesday, 31 March 2026

Counting in business days instead gives 10 April 2026, because ten weekend days fall in between.

What happens to your data

This tool runs entirely in your browser. Your input is never uploaded to a server, never stored, and never logged. Dates are worked out with the browser's own Date object; nothing is sent anywhere, and the tool never learns what the deadline is for.

Last updated August 2026

Two questions account for almost all date arithmetic: what date is thirty days from now, and how many days are there between these two dates. Both are easy to get wrong by hand and easy to get wrong in a spreadsheet, because months are not a fixed length and weekends are not always excluded.

This does both, in calendar days or in business days that skip Saturdays and Sundays. It opens on today, so the common case — a deadline counted from now — takes one number.

The question behind most disagreements about dates is whether you are counting days or counting boundaries. From Monday to Wednesday is two days if you count the nights and three if you count the dates. Neither is wrong, and which one applies depends on what is being measured: a hotel bills the nights, a deadline of three days from Monday usually means Thursday, and a document that says within 3 days rarely says which it means. When a date matters, it is worth settling that question first — the arithmetic is the easy half.

How it works

Toolvore works in local calendar dates rather than instants. That distinction matters more than it sounds: parsing "2026-03-29" produces midnight UTC, and adding twenty-four hours to it lands on the same calendar day for anyone west of Greenwich on the night the clocks change. Building the date from its year, month and day components and stepping the day component keeps every answer in the terms the question was asked in. Adding months clamps rather than rolls over, so one month after 31 January is the last day of February and not the third of March. Business days here mean Monday to Friday and nothing else. Public holidays are not deducted, and they cannot be without knowing which country, and often which state or region, you are in — a working-days figure that quietly assumed the wrong calendar would be worse than one that is clear about what it counts. Where a deadline runs in working days and holidays fall inside the window, take the answer here and subtract them by hand.

Common use cases

Working out a contractual deadline — 30, 60 or 90 days from a signature date
Counting the days between today and an exam, a due date or a flight
Adding business days to a date when a process is quoted in working days
Checking a notice period that runs in weeks or months rather than days
Finding a date a fixed number of years back, for eligibility or record-keeping
Counting the days between two dates for an invoice or an interest calculation
Checking how long is left before a passport, visa or warranty expires

Frequently asked questions

Does the count include the start date?＋

No. Counting between two dates excludes the start and includes the end, which is the convention for a deadline expressed as "30 days from" something. So 1 March to 31 March is 30 days.

What counts as a business day?＋

Monday to Friday. Public holidays are not excluded, because they differ by country and by region — guessing which apply to you would be worse than telling you plainly that they are not included.

What happens when I add a month to the 31st?＋

It clamps to the last day of the target month. One month after 31 January is 28 or 29 February, not 2 or 3 March — which is what JavaScript's date arithmetic would otherwise produce.

Does daylight saving affect the result?＋

No. Everything is computed on calendar dates rather than timestamps, so a clock change during the range cannot shift the answer by a day.

Is my date sent anywhere?＋

No. The arithmetic happens in your browser using its own date functions. Nothing is uploaded, and the tool never learns what the deadline is for.

Why does my answer differ by one day from someone else's?＋

Almost always because one of you counted the start date and the other did not. Between the 1st and the 10th there are nine days of elapsed time and ten dates involved. Contracts and regulations usually specify which they mean — clear from, excluding the day of, and inclusive of both dates all pick a side. Where nothing specifies it, elapsed days is the more common reading.

Does it account for public holidays?＋

No, and deliberately. Holidays differ by country, by region and by year, and a calculator that guessed would give a confident wrong answer to someone relying on it for a deadline. Business days here means weekdays. If your working calendar excludes more than weekends, count those days off the result yourself.

How should I count a notice period given in months?＋

By date rather than by days, in most cases. Three months from 15 January is 15 April, not 90 days later — the two differ by a day or more depending on which months are involved. The awkward case is a period starting on the 29th, 30th or 31st, where the target month may not have that date; conventions differ, and the common one is to fall back to the last day of that month.

Does it handle leap years?＋

Yes, including the rule most people forget. A year divisible by 4 is a leap year, except one divisible by 100, unless it is also divisible by 400 — which is why 1900 had no 29 February and 2000 did. Any span crossing a 29 February is one day longer than the same span in an ordinary year, which is enough to move a deadline.

How do I work out an age correctly?＋

Count the years to the most recent birthday rather than dividing days by 365. Someone born on 3 September 2000 is 25 until 3 September 2026 and 26 the moment it arrives, and the day-division method drifts by a day or more because leap years make the average year 365.2425 days. The edge case is a 29 February birthday, where common practice in most places treats 1 March as the birthday in non-leap years — though the legal answer varies by country.