Date Calculator
Two date jobs in one place: count the exact days between two dates, or start from a date and add or subtract days, weeks, months and years to land on a new one.
Calculate with dates
Both dates start on today — change either one to begin.
Your dates result will appear here.
Both date jobs, done with the real calendar
Exact gaps between dates, and dates moved by days, weeks, months or years.
Days between dates
The exact gap in days, also broken into years, months and days, weeks, and hours for the curious.
Date adder and subtracter
Notice periods, deadlines, expiry dates: 90 days from signing, 6 months before a renewal, 2 weeks after delivery.
Calendar-true results
Leap years, 31-day and 30-day months and month-end clamping are all handled by real calendar rules.
About the date calculator
Date arithmetic looks simple until the calendar gets involved: months have four different lengths, February changes in leap years, and “three months from 31 January” has no obvious answer. This calculator does both everyday date jobs with real calendar rules — the exact number of days between two dates, and adding or subtracting days, weeks, months or years from a starting date.
The days-between count is the one behind countdowns, deadline checks and “how long until” questions: days until a wedding or an exam, days since a start date, the length of a notice period. The result is shown as a total in days and broken down into years, months and days, plus weeks and hours. The count excludes the starting day itself — the convention most deadlines use — so two dates on consecutive days are one day apart.
Adding months and years needs a rule for month ends, and this page uses the standard one: if the target month is shorter, the result is its last day. One month after 31 January is 28 or 29 February; one year after 29 February is 28 February in a non-leap year. The rule is stated on the page rather than hidden, because for contracts and renewals the edge cases are exactly the cases that matter.
Frequently asked questions
Counting rules, leap years and month ends, answered.
How are the days between two dates counted?
As the number of midnights between them, excluding the start day — so Monday to Tuesday is 1 day. That matches how most deadlines and countdowns are counted.
Does it handle leap years?
Yes. The maths runs on the real calendar, so 29 February is counted in leap years and month lengths are exact.
What happens adding a month to 31 January?
It lands on the last day of February — the 28th, or the 29th in a leap year. That is the standard calendar rule, and the page states it openly.
Can I count backwards?
Yes. Subtract mode moves a date backwards, and the between count accepts the two dates in either order.
Does it count working days only?
No — it counts calendar days, including weekends. Working-day counts depend on each country holidays, so they are not guessed at here.
Is any data stored?
No. The dates are calculated in your browser and nothing is sent or saved.