Date Calculator
A date calculator for questions like what date is 90 days from today. Add or subtract days, weeks, months or years, and get the weekday with the answer.
How to use
- Leave Start date on today for a count from now, or type the day you're counting from.
- Pick Add or Subtract, put a figure in Amount, and set Unit to days, weeks, months or years.
- Tick Working days only to count Monday to Friday, and list any holidays in the box that appears, one date per line.
- Read the resulting date and its weekday. The shortcut cards under it are a one-tap version of all three steps for the common day counts.
About this tool
Ninety days from today is what date? A date calculator earns its keep on that one question, so the page answers it before you touch anything. Start date opens on today, Amount opens on 90, and the answer is filled in the moment it loads. Change any field and it redraws on the keystroke.
Under the answer sit eleven shortcut cards, for 7, 10, 14, 21, 30, 45, 60, 90, 100, 120 and 180 days, each already showing the date it leads to and a weekend tag where it lands on a Saturday or Sunday. Following one is a reset as much as a shortcut. The page reloads with the start date on today, the unit on days and the direction back on Add, whatever you had typed before. Each carries a plain days address of its own, so a bookmark to 30 days from today keeps answering correctly next month.
Days and weeks roll over the end of a month without any fuss. Months and years go by the calendar instead, keeping your day number wherever the target month has one and clamping to the last day where it doesn't. Add a month to 31 January and you land on 28 February, or the 29th in a leap year, and the line under the answer says the day clamped. Clamping is the right answer and it also throws information away, which is why the round trip isn't symmetric: 31 January forward a month then back a month leaves you on 28 January.
The answer spells the month out in words rather than digits, the way your browser writes dates, which takes the ambiguity out of something like 10/11/2026, and the weekday sits beside it. Tick Working days only and the count skips weekends and any holidays you list, with each listed line reported back. The address bar keeps up as you type, direction included, and Copy share link copies exactly that address.
Sixty days' notice on a flat, and the lease that follows it
Notice goes in on Monday 31 August 2026 and the agreement asks for sixty days. Set Start date to that Monday, leave Direction on Add, type 60 and keep Unit on days. The answer reads 30 October 2026, a Friday, which is a comfortable day to hand over keys. Days are counted one at a time across the month ends, so the 30 days of September and the 30 of October fall where the calendar puts them.
The new place is a six-month lease from the same 31 August, so switch Unit to months and Amount to 6. February has no 31st, and 2027 lends it no 29th either, so the day clamps and the answer reads 28 February 2027, a Sunday, with a line under it saying the day clamped to the 28th and that six months back lands on 28 August. That is three days short of where you began, because the clamp threw the 31 away for good.
Before you rely on it
- Working days mean Monday to Friday. No country's public holidays are built in, so a holiday counts as a working day until you type it into the box, and a Sunday-to-Thursday week is not offered.
- Month arithmetic clamps to the end of a short month, and clamping loses the original day number. 31 March back one month is 28 February, and adding the month again returns 28 March.
- One shift per pass. Something like ninety days out and then forward to the next Monday needs two goes.
- Amount takes whole numbers only. A minus sign in front flips Direction rather than being refused, and the largest amount is whatever keeps the answer inside the years 1 to 9999.
Frequently asked questions
What date is 90 days from today?
It is already on screen. Start date holds today and Amount holds 90 the moment the page opens, so the answer sits at the top before you type. Swap 90 for any other number, or press one of the shortcut cards under it.
How does adding a month to the 31st work?
It keeps your day number when the target month is long enough and clamps to the final day when it isn't. 31 January plus one month gives 28 February, or the 29th in a leap year. 31 March plus one month gives 30 April. Weeks and days are simpler: they count forward and cross whatever boundaries they hit.
Does it show which weekday the answer falls on?
It sits beside the date, in full. When the answer lands on a Saturday or Sunday, the line under it names the working day before and after, because a weekend deadline usually means the Friday before it in practice.
How do I count backwards to a date in the past?
Set Direction to Subtract and everything else behaves the same way. A minus sign typed in front of the amount does the same job: Direction flips and the sign comes off.
Does a copied link keep the direction?
It does. The address bar carries the start date, the amount, the unit, the direction and whether Working days only is ticked as you type, and Copy share link copies that address, so the link and the page cannot disagree. The holiday list stays on your screen only.
What happens when the amount isn't a whole number?
The answer stays where it was, dimmed, under a line saying it is held for the last amount that made sense, and the Amount field says why, as in a month has no half. Copy share link waits until the amount reads again. Day and week arithmetic runs on UTC calendar days, so a daylight-saving weekend in your zone never shortens or lengthens a count.
Should I use this or the countdown timer?
Use this when you want the date itself, a fixed answer that stops moving once you have it. The countdown tool is for a live clock running down to a moment you have already chosen. Working out the date here and then handing it over is the usual order.
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