A date calculator for deadlines, notice periods and countdowns
Most date questions come in one of three shapes. What date is 90 days from today? How long is it from this date to that one? How many days are left until the wedding? Simple Date Calculator puts all three on one small window, under three tabs: Add or subtract, Between dates and Days until.
Whichever tab you are on, the figures change the moment you touch a date or a number. A large rolling counter at the top shows the count, and the dates sit in plain fields below it. There is no Calculate button to press and no page to reload.
It sits on the desktop rather than in a browser tab, remembers the dates and amounts you used last, and copies any result to the clipboard with a single click on the counter.
How to add days to a date, or subtract them
Open the Add or subtract tab and work down the window:
- Set the Date, or press Today to start from the current day.
- Choose Add or Subtract.
- Type an amount, any whole number from 0 to 99,999.
- Pick the unit: Days, Weeks, Months or Years.
- Read the Result date, shown with its day of the week.
Adding months to a date, done the way calendars expect
Days and weeks are simple arithmetic. Months are not, because they are different lengths, and this is where many online tools quietly go wrong. Add one month to January 31 and some calculators roll over into early March.
Here the result stays inside the month you asked for. If that month is shorter than the start date's day, you land on its last day instead, so January 31 plus a month gives the end of February. Years follow the same rule for leap days. That matters for contract terms, subscription renewals, probation periods and anything else written as "one month from" a date.
A days until calculator for birthdays and events
The Days until tab counts from today to a date you choose. Type a name in Event, such as Moving day or Exam, so the counter is labeled, and watch the number drop by one each midnight even if the window stays open.
For dates that come round every year, tick Repeat every year, for birthdays and anniversaries. The count then always aims at the next occurrence, and the day after the event it starts on the following year's.
Need the gap between two fixed dates instead? The Between dates tab shows it in days on the counter, as years, months and days on a smaller dial, and in weeks, months, hours, minutes and seconds underneath.
