Date Difference Calculator
Count the exact days between two dates, with the gap also shown in weeks and calendar months.
How it works
days = second date − first date · weeks = days ÷ 7 · months by calendar walking
The day count is the exact number of calendar days from the first date to the second, so consecutive days are 1 apart and the start date itself is not added in. Weeks are simply days divided by seven with the remainder shown. The month breakdown walks real calendar months — a month is however long the calendar says, never a flat 30 days — so it lands on the same day-of-month before counting leftover days.
Worked example
From January 1, 2026 to September 11, 2026: 253 days, which is 36 weeks, 1 day. Walking the calendar, 8 whole months reach September 1 and 10 days remain — 8 months, 10 days.
Frequently asked questions
Why do some tools show one day more?
They count inclusively — both endpoint dates — which suits questions like “how many days of a rental”. This calculator counts elapsed days between the dates; add 1 if you want both ends included.
How can the months figure disagree with days ÷ 30?
Because calendar months run 28 to 31 days. Walking real months is what makes “January 15 to March 15” exactly 2 months, which a 30-day approximation misses.
What if I enter the later date first?
The dates are swapped automatically and the summary notes it, so the result is always a positive gap.
Related calculators
This calculator is for educational purposes. Double-check important results before acting on them.