Date & Time Tools New Tool

Free Online Add or Subtract Days from a Date, Weeks, Months & Years

Find the date a number of days, weeks, months or years from another date, forwards or backwards. Month ends are handled the way banks and rent do it, so 31 January plus one month is 28 February rather than 3 March, and the tool says which rule it used.

Free Forever Nothing Uploaded Step by Step Real Calendar Months

Free Online Add or Subtract Days from a Date, Weeks, Months & Years

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📆 Add or Subtract Time Days, weeks, months and years · the step by step shown

Every date is worked out in your browser. Nothing you type is sent anywhere.

📆 Start from

Date

Direction

How much

Years

Months

Weeks

Days

Fill in as many as you need. Years and months are applied first and land on the calendar; weeks and days are then counted one at a time.

Try one of these

The date you land on

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Recent date sums, kept in this browser only.

Nothing here yet Press Log to history on the Add or subtract tab to keep an answer here. Load one back with the arrow button.

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What Is One Month After the 31st of January?

There is no 31st of February, so something has to give.

Two answers are defensible. You can clamp, and land on the 28th, because the end of one month should be the end of the next. Or you can roll over, and land on the 3rd of March, because 31 days after the 31st of January is the 3rd of March. Banks, rents, salaries and subscriptions almost always clamp, so that is what this page does, and it says so on every answer where it happens.

Start	Add	Clamped, as here	If it rolled over instead
31 Jan 2026	1 month	28 Feb 2026	3 Mar 2026
31 Jan 2024	1 month	29 Feb 2024	2 Mar 2024
30 May 2026	9 months	28 Feb 2027	2 Mar 2027
29 Feb 2024	1 year	28 Feb 2025	1 Mar 2025

Adding a month and then taking it away does not always bring you home. The 31st of January plus one month is the 28th of February, and the 28th of February minus one month is the 28th of January. That is not a bug in the arithmetic. It is what happens when you use a unit that changes length.

The order matters, so it is fixed and shown. Years and months go on first, then weeks and days. Do it the other way round and the 30th of January plus one month plus one day can land on a different date entirely. The step table under the answer shows each stage.

How to Use the Add and Subtract Days from Date

Four steps, and the second one is where the order starts to matter.

Pick the date you are starting from The Start from today button fills it in with the browser date, which is what most people arriving here want. The weekday, the day of the year and the ISO week number appear underneath it.

Choose add or subtract, then fill in the amounts Years, months, weeks and days can all be used together. Years and months are applied first and land on the calendar, then weeks and days are counted on top. That order is fixed, and the step table shows each stage.

Read the answer, and the note when there is one If the day of the month did not exist in the month it arrived at, the answer stops at the last day of that month and says so. This is the behaviour banks and landlords use.

Carry the answer forward if you need to chain sums Use it as the start moves the result into the start box and clears the amounts, so a series of steps can be worked through without copying dates by hand.

What to Know Before You Start

Including the things this tool cannot do.

A month is not 30 days here. Adding one month to the 15th of any month gives the 15th of the next one, whether that month is 28, 30 or 31 days long. Tools that quietly add 30 days give a different answer for most of the year.

Months clamp, they do not roll over. The 31st of January plus one month is the 28th of February, not the 3rd of March. That is the convention used for rent, salaries, interest and subscriptions, and the answer tells you every time it happens.

Adding then subtracting may not return you to the start. Plus one month from the 31st of January is the 28th of February; minus one month from there is the 28th of January. This is a property of calendar months rather than a fault in the arithmetic, and no tool can avoid it.

The order is years and months first, then weeks and days. Reversing it can change the answer by a day or two around the ends of short months. The order used here is written down and shown step by step rather than left for you to guess.

Every day counts, including weekends. This is a plain calendar count. If you need to skip weekends and public holidays, the working days calculator on this site does that and shows you which days it removed.

There are no hours or minutes here. Everything runs on whole calendar dates, which is exactly what stops a daylight saving change from moving an answer by a day. For a deadline that falls at a particular time of day, add the time separately.

Key Features & Capabilities

What this tool does, and what it deliberately does not.

Real calendar months Months and years land on the calendar and clamp to the end of short months, the way contracts and banks work.

Every step shown A table of what was applied, the date after each stage and a note when a date had to be clamped.

Add and subtract The same panel both ways, so working backwards from a deadline takes one click rather than a rewrite.

Chain sums together Carry the answer back into the start box and keep going, without copying dates by hand.

Nothing leaves the page No server, no account and no upload. Saved setups and history live in this browser and can be cleared from Settings.

Saved setups and history Keep the sums you repeat and load one back with a single button.

About the Add and Subtract Days from Date

Adding days to a date is easy. Adding months is where calculators quietly disagree with each other. Some add 30 days and call it a month, which is wrong eleven times out of twelve. Some land on the calendar but roll over the end of short months, so the 31st of January plus one month becomes the 3rd of March. This page lands on the calendar and stops at the last day of the month instead, because that is what a bank, a landlord and a payroll system all do, and it tells you on the answer whenever that adjustment was needed.

The order of operations is fixed and visible. Years and months are applied first, then weeks and days are counted on top of the result. It has to be one way or the other, because the two orders genuinely give different answers near the ends of short months, and a tool that does not say which one it used is asking you to trust a number you cannot check. The step table under the answer shows the starting date, each stage and the date it produced.

Underneath, the days part of the sum is a plain addition on a day number counted from the first of January 1970. That is why leap days need no special handling: the 29th of February is simply a day that exists in some years and not others, and counting through it is the same as counting through any other day. It is also why nothing here shifts by a day when the clocks change, which is a common and almost invisible fault in calculators that work in hours or milliseconds.

Frequently Asked Questions

Everything worth knowing before you trust the answer.

Press Start from today, leave the days box at 30 and the answer appears immediately. Because this is a plain count of days rather than a month calculation, the result is exactly 30 days later whatever month you are in.

The 28th of February, or the 29th in a leap year. February has no 31st, so the date stops at the last day of that month instead of spilling over into March. This is called clamping, and it is what contracts, rents and subscriptions do. The alternative convention gives the 3rd of March, and the page shows both so the difference is clear.

Because months are not all the same length. The 31st of January plus one month is the 28th of February, and the 28th of February minus one month is the 28th of January, not the 31st. Information is lost the moment a date is clamped, and no arithmetic can recover it.

Years and months first, then weeks and days. The order matters near the ends of short months, so it is fixed rather than left to chance, and the step table under the answer shows the date after each stage.

No. This is a plain calendar count, so every day counts. The working days calculator on this site skips whichever days you tell it to and lists the ones it removed.

Yes. Switch to Subtract and fill in the same boxes. To work through several steps, use the Use it as the start button to move each answer into the start box.

Yes, without any special case. Days are counted on a day number, so the 29th of February is just a day that exists in some years. One year after the 29th of February 2024 is the 28th of February 2025, because there is no 29th to land on.

No. Adding or subtracting days is calendar arithmetic done in this tab, leap years included. Saved setups and history are kept in this browser only, which also means clearing them from the Settings tab is final.