Date Difference Calculator
Calculate the exact years, months, and days between two dates, plus total days, weeks, and months.
What this calculator does
Calculates the exact gap between two dates two ways: a calendar-accurate years/months/days breakdown, and a running total in days, weeks, months, and years — useful depending on whether you need a precise breakdown or a single overall figure.
Who this is for
Anyone counting down to or measuring from an event (wedding, deadline, anniversary), calculating a contract term or notice period, or working out how much time has passed since or until a specific date.
How this calculator works
Shows the calendar-accurate breakdown first — the exact number of full years, full months, and remaining days between your two dates, calculated the same way birthday and anniversary counts work (accounting for varying month lengths and leap years). Below that, it also shows the total days, weeks, months, and years as running totals, which are useful for things like contract terms or notice periods where you need a single overall figure rather than a broken-down count.
Worked example
From January 15, 2024 to July 6, 2026: that's 2 complete years (Jan 2024 to Jan 2026), 5 complete months (Jan to June 2026), and 22 remaining days (June 15 to July 6) — giving 2 years, 5 months, 22 days. As a single running total, that same gap is approximately 905 days, or about 29.7 months using the 30.44-day average.
Common mistakes
- Confusing the two month figures. The main "years, months, days" result uses real calendar months (so "2 months" always means 2 actual calendar months). The separate "Total months (approx)" figure further down uses a 30.44-day average instead, since it's expressing the whole gap as a single decimal number — the two won't match exactly, and that's expected.
- Forgetting to include or exclude the start date. Depending on context (contract terms, notice periods, age calculations), you may need to count inclusively or exclusively — check which convention applies to your specific use case.
- Mixing up which date is first. The calculator handles either order automatically, but double-check your inputs if the result looks unexpectedly large or small.
- Using the approximate total for a legally precise count. For contracts, notice periods, or anything requiring exact day counts, use the calendar-accurate breakdown at the top, not the 30.44-day-average approximation below it.
Related calculators
Related reading
Frequently Asked Questions
Which figure should I use for a legal contract or notice period?
Use the calendar-accurate "years, months, days" breakdown at the top, not the approximate running totals — the approximate figures use a 30.44-day monthly average, which isn't precise enough for legally binding date calculations.
What's the difference between the "years, months, days" figure and "total months"?
The headline "years, months, days" is a calendar-accurate breakdown — the same way you'd count someone's exact age. The "Total months (approx)" and "Total years (approx)" figures further down instead express the entire gap as one decimal number, using a 30.44-day average per month, which is useful when you need a single figure rather than a broken-down count.
Does it matter which date I enter first?
No, the calculator automatically works out which date is earlier and shows the difference in the correct order regardless of which field you filled in first.
Does this include or exclude the start date?
The day count is the calendar difference between the two dates. If you need an inclusive count (counting both the start and end day), add 1 to the result.