Age Calculator
Calculate age between a birth date and a selected date in completed years, months, and days.
How it works
Compare the two calendar dates, count completed years first, then completed months, then the remaining whole days. Calendar month lengths and leap years are handled by date arithmetic rather than a fixed days-per-year estimate.
Formula / calculation method
Count completed calendar years from birth date to comparison date.From the year-adjusted date, count completed months.Count the remaining calendar days.
Worked examples
- A birth date of 1 January 2000 to 1 January 2026 is exactly 26 years.
- A birth date of 15 June 2000 to 20 August 2026 is 26 years, 2 months, and 5 days.
When this tool helps
Useful for birthdays, eligibility checks, school or sports age references, records, forms, and any situation that needs completed calendar age rather than an approximate decimal year.
Related calculations: days between dates and time duration calculator.
Browse this topic: Education, Age & Date Calculators · GPA, Grade & Date Calculation Guide.
Quick reference
| Input | Result |
|---|---|
| 2000-01-01 → 2026-01-01 | 26 years |
| 2000-06-15 → 2026-08-20 | 26 years 2 months 5 days |
| 2024-02-29 → 2025-02-28 | 1 completed year |
Accuracy and definitions
This calculator uses calendar dates. It does not assume every year has 365 days or every month has the same length. Leap-day birthdays are clamped to the last valid day when a comparison year has no February 29.
Methodology & verification
- Method
- Compare the two calendar dates, count completed years first, then completed months, then the remaining whole days. Calendar month lengths and leap years are handled by date arithmetic rather than a fixed days-per-year estimate.
- Verification
- The displayed formula is cross-checked against Solveberry regression cases before release. Calculator inputs and results stay in the browser.
- Last reviewed
- 2026-08-19
Results are calculated locally in your browser. Optional analytics do not include calculator input values or results.
Common questions
Does this account for leap years?
Yes. The calculation uses real calendar dates and month lengths, including leap years.
Can I calculate age on a past or future date?
Yes. Choose any comparison date that is on or after the birth date.
How does the calculator handle calendar boundaries?
The method is shown on the page. Date calculations use explicit calendar dates rather than assuming every month has the same length.
Does this replace an official deadline or age determination?
No. For legal, eligibility or contractual decisions, verify the result against the rule or authority that defines the relevant date or age.