Date & time Difference

Years between dates

From

Counting

Years —

The same gap in other units

Days —

Weeks —

Whole weeks —

Months —

Years, months, days —

Hours —

Minutes —

Note Enter both dates

Complete anniversaries only

A complete year runs from a date to the same date the following year. From 1 January 2000 to 31 December 2026 is 26 complete years, because the twenty-seventh has not finished — the anniversary falls the next day.

How to count years between dates

1 Enter both dates.

2 Read the complete years.

3 The breakdown shows the leftover months and days.

4 An anniversary counts on the day, not the day before.

The completed-year convention is why an age ticks over on a birthday rather than at any point during the year. It is also why 29 February birthdays are a genuine legal question: in England a leapling legally turns 18 on 1 March, while in some other jurisdictions it is 28 February. The arithmetic here follows the common convention of the anniversary date, clamped to 28 February in a common year.

Questions

How many years between two dates? −

Count complete anniversaries. The final year counts only once its anniversary has passed.

Why is 31 December to 1 January only one day? +

What about a 29 February birthday? +

How do I get a decimal year? +

Is a year always 365 days? +

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INTERNAL SIGNAL ONLY · WE USE IT TO FIND TOOLS WORTH REBUILDING