Date Difference Calculator
Find the difference between two dates in days, weeks, months, and years
Finds the time span between two dates, shown simultaneously in days, weeks, months, and years, updating instantly as you pick either date.
How it works
The day count is exact — a straightforward count of calendar days between the two dates. Weeks, months, and years are each that same day count divided by an average unit length (accounting for leap years via the 365.2425-day average year), rather than a calendar-aware breakdown like the Age Calculator's — so they're consistent, sensibly-rounded conversions of one span, not four numbers that add up to each other.
Frequently asked questions
Why don't the weeks/months/years numbers add up the way the Age Calculator's years/months/days do?
This tool shows the same total span converted into four different units independently, using average unit lengths for weeks/months/years — it's not meant to decompose into a single years-plus-months-plus-days breakdown the way Age Calculator does. Both are accurate; they just answer different questions.
Does the order I pick the two dates in matter?
No — the result is always the absolute difference between them, so picking Date A after Date B gives the same result as the other way around.
How precise are the months and years figures?
They're rounded to one and two decimal places respectively, using average month/year lengths — precise enough to be useful, but not meant to represent an exact calendar breakdown the way a whole-number years/months/days count would.
What happens if I only fill in one date?
Nothing is calculated yet — a result only appears once both dates have a value, rather than showing a partial or placeholder number.
Is my date data sent anywhere?
No — the entire calculation happens locally in your browser. Nothing you enter is uploaded or stored.