Years Between Dates
Calculate the exact number of years, months, and days between two dates.
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How to use this calculator
- 1
Select the start date.
- 2
Select the end date.
- 3
The result shows complete years, remaining months and days, plus a decimal years value.
Frequently asked questions
How does this tool split the gap into years, months and days?
It uses the shared date utilities. Whole calendar months are counted forward from the start date and the leftover is reported in days. The months total is then divided into years and a remainder. January 1, 2020 to March 15, 2023 is 3 years 2 months 14 days.
What is Decimal Years?
It is total days ÷ 365.25, shown to four decimals. For February 29, 2000 to February 28, 2026 that is 9,496 days, or 25.9986 years, even though the breakdown reads exactly 26 years. Use the breakdown for ages and anniversaries, and the decimal for rate calculations that specify a year-fraction.
How are leap days and February 29 start dates handled?
When a target month is too short, the date is clamped to its last day, so the anniversary of February 29 in a common year is February 28. From 2000-02-29 to 2026-02-28 the result is 26 years 0 months 0 days, and one day later, on March 1, 2026, it is 26 years 0 months 1 days.
What happens if the end date is before the start date?
The breakdown is wrapped in a minus sign, for example −(0 years 1 months 1 days) for March 1 back to January 31, 2026, and the decimal years and total days show a minus sign too. The size of the gap is the same as in the forward direction.
Does it count the start and end days inclusively?
No. It measures the distance between the dates, so the same date on both sides is 0 years 0 months 0 days. Add one day yourself if your document counts both end dates.
Can I use it to work out someone’s exact age?
Yes, put the birth date as the start and the reference date as the end. A birth date of 1990-05-15 and an end date of 2026-11-03 gives 36 years 5 months 19 days. The tool compares calendar dates only, so it does not use birth time or time zones.
Why is the day total larger than 365 times the years?
Because leap days add extra days. February 29, 2024 to February 29, 2028 is four years but 1,461 days, which is 4 × 365 plus one leap day, and the decimal reads 4.0000 with the 365.25 divisor.
What happens with blank or invalid dates?
The tool returns a dash instead of guessing a date, so check that both pickers are filled.
Years between dates — breakdown, decimal years and total days
Two ways to express the same gap
A long span can be quoted as years, months and days or as a single decimal. The first is how people talk about age, tenure and anniversaries: thirty-six years, five months and nineteen days. The second suits formulas that need a year fraction, such as annualised returns or depreciation. The calculator reports both, plus the total day count, so you can use whichever your document requires. The breakdown comes from stepping forward in whole calendar months, while the decimal divides days by 365.25, so the two will rarely match exactly.
Worked examples
Seven date pairs with fixed values were run through the calculator. The table lists the breakdown, decimal years and total days for a typical age, an ordinary multi-year span, four leap-day cases and a reversed pair.
| Start | End | Years, months, days | Decimal years | Total days |
|---|---|---|---|---|
| 1990-05-15 | 2026-11-03 | 36 years 5 months 19 days | 36.4709 | 13,321 |
| 2020-01-01 | 2023-03-15 | 3 years 2 months 14 days | 3.2005 | 1,169 |
| 2000-02-29 | 2026-02-28 | 26 years 0 months 0 days | 25.9986 | 9,496 |
| 2000-02-29 | 2026-03-01 | 26 years 0 months 1 days | 26.0014 | 9,497 |
| 2024-02-29 | 2028-02-29 | 4 years 0 months 0 days | 4.0000 | 1,461 |
| 2024-02-29 | 2025-02-28 | 1 years 0 months 0 days | 0.9993 | 365 |
| 2026-03-01 | 2026-01-31 | −(0 years 1 months 1 days) | −0.0794 | −29 |
Why the decimal drifts from the breakdown
The third row is the clearest illustration. The breakdown says exactly 26 years, but the span is 9,496 days, and 9,496 ÷ 365.25 is 25.9986 rather than 26. The averaging divisor treats every year as 365.25 days, and a particular run of years may contain fewer or more leap days than that average predicts. The gap is tiny, but if a contract defines elapsed time as a calendar count, use the breakdown, and if it defines a day-count fraction, use the decimal.
Leap-day anniversaries
Someone born on February 29 has no February 29 birthday in a common year. This tool treats February 28 as the anniversary: the 2000-02-29 to 2026-02-28 span is a full 26 years, and the next day is 26 years and 1 day. Legal systems differ on which date counts, so for official age rules check the one that applies to you. For four-year leap cycles the match is exact, as the 2024 to 2028 row shows.
Scope of the calculation
Only calendar dates are compared, with no times, time zones or holidays, and the end date is not counted as an extra day. A reversed pair gives the same-sized gap behind a minus sign. For weeks or months instead, use the matching pages, and if you need the exact date a number of years ahead, use the date calculator.
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Results are estimates for informational purposes only and do not constitute professional financial, medical, legal, or technical advice. Read full disclaimer →