What is 90 days from today?

Enter today's date in the start date field, choose Add, type 90 in the Days box, and read the result. The calculator accounts for different month lengths, so you don't have to count manually.

How do I add months to a date by hand?

Move the month number forward by the amount you want. If the resulting month has fewer days than the original day number, use the last day of that month instead. For example, 31 January + 1 month = 28 February (or 29 February in a leap year).

How does the calculator handle leap years?

A year is a leap year if it's divisible by 4 — except century years (like 1900), which must also be divisible by 400. The calculator checks this automatically, so adding or subtracting years across a leap year like 2024 gives the correct date without any extra input from you.

Is my data saved or sent to a server?

No. Everything runs in your browser. No date you enter is uploaded, stored, or shared anywhere.

Can I calculate the number of days between two dates?

This tool shows you a result date after adding or subtracting a duration. To count how many days fall between two specific dates, you need a 'days between dates' or date difference calculator.

Does this count calendar days or business/working days?

Calendar days only — every day of the week counts, including weekends and public holidays. If you need to skip weekends or bank holidays, you'll need a dedicated business-day calculator.

What happens when I add days past the end of a month?

Days overflow naturally into the next month. For example, 25 April + 10 days = 5 May. Only month and year additions can hit an end-of-month clip; adding plain days always gives the exact right date.

Is this date calculator free?

Yes, completely free with no sign-up required. Open the page, use the tool as many times as you like.

Date Calculator – Add or Subtract Days, Months & Years

Find any past or future date in seconds

Pick a starting date, choose whether to add or subtract, then enter the number of days, months, or years you need. The date calculator handles all the tricky bits — uneven month lengths, leap years, end-of-month edge cases — and gives you the exact result date instantly.

It runs entirely in your browser, so nothing you enter is sent anywhere or stored.

How to use the date calculator

Enter your start date — today's date is filled in automatically, but you can change it to any date.
Choose Add or Subtract — adding moves you forward in time; subtracting moves you back.
Enter the number of days, months, and/or years you want to move by. You can mix them (e.g. 1 year, 3 months, and 10 days all at once).
Read the result date — it appears immediately below the inputs.

Worked example: 90 days from today

Suppose today is 15 April 2025 and you need to know what date falls exactly 90 days later — a common deadline in contracts, trials, and visa rules.

Start date: 15 April 2025
Operation: Add
Days to add: 90
Result: 14 July 2025

Counting 90 days by hand means remembering April has 30 days, May has 31, June has 30, July has 31 — easy to get wrong. The calculator does it in one click.

Now flip it: what date was 90 days before 15 April 2025?

Start date: 15 April 2025
Operation: Subtract
Days to subtract: 90
Result: 15 January 2025

How the calculation works

The engine converts your start date into an internal day count, adds or subtracts the exact number of days, then converts back to a calendar date. Month and year amounts are applied first (moving the calendar month/year pointer), then the remaining days are added on top.

Result = StartDate + (Years × 365.2425) adjusted to calendar
Result = StartDate + Months → move the month pointer
Result = intermediate date + Days

In plain terms: adding 1 month means moving the month digit forward by one and keeping the day the same — unless the new month is shorter (e.g. 31 January + 1 month = 28 February in a non-leap year, or 29 February in a leap year).

Leap years (divisible by 4, except century years not divisible by 400) add one extra day in February. The calculator knows every leap year automatically.

What you're calculating	Example	Result
Days from a date	15 Apr 2025 + 30 days	15 May 2025
Months from a date	15 Apr 2025 + 6 months	15 Oct 2025
Years from a date	15 Apr 2025 + 2 years	15 Apr 2027
Days before a date	15 Apr 2025 − 90 days	15 Jan 2025
End-of-month edge	31 Jan 2025 + 1 month	28 Feb 2025
Leap year Feb	29 Feb 2024 + 1 year	28 Feb 2025

When people need a date calculator

The same underlying question comes up in many different situations. Here are the most common ones and how to phrase them:

'What date is X days from now?' — Use Add, enter only the days field. Classic for payment due dates, return windows, and subscription trials.
'What date was X days ago?' — Use Subtract. Useful for auditing when something happened, or backdating a record.
'Add months to a date' — Monthly billing, lease renewals, or any rolling 3/6/12-month period. Use the months field on its own.
'Days between two dates' — This tool shows the result date; if you want the count of days between two specific dates, use a days-between-dates calculator instead.
'Future date after X years' — Warranty expiry, passport renewal, or long-term project planning.

Quick tips and common mistakes

Mixing units is fine. You can add 1 year, 6 months, and 15 days in one go — you don't need to do separate steps.
Month lengths catch people out. Adding 1 month to 31 March gives 30 April, not 31 April (that date doesn't exist). The calculator clips to the last valid day of the month automatically.
Leap day edge case: 29 February 2024 + 1 year lands on 28 February 2025, because 2025 is not a leap year.
Don't confuse 'add days' with 'add business days'. This tool counts calendar days (including weekends and public holidays). If you need working days only, you need a business-day calculator.
Double-check your start date. The most common error is forgetting to update the start date from today when you need a historical calculation.

Your data never leaves the browser — every date is calculated locally, with no server involved and nothing stored.

The date calculator above is the fastest way to get the right answer without counting on your fingers. Try it now — just enter your start date and how far you want to move.