How it works
Enter a birth date and the date on which you want to calculate age. Leap-year birthdays are treated using the relevant calendar date where possible.
FormulaAge = full calendar years elapsed since birth.
EVERYDAY / DATES
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Calculate completed years alive, the approximate number of days lived and days until the next birthday.
Your numbers
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YOUR RESULT
Enter your numbers to see a result.
Age calculator: a worked example
With date of birth 2000-01-01, calculate as of 2026-01-01, the completed years is 26 years.
| Date of birth | 2000-01-01 |
|---|---|
| Calculate as of | 2026-01-01 |
| Completed years | 26 years |
|---|---|
| Days lived | 9,497 days |
| Days until next birthday | 0 days |
Amounts are shown in US dollars for illustration. Choose your own currency in the calculator above; it labels amounts and does not convert them.
Make the numbers useful
Try changing one input at a time. The live result helps you see which assumption has the greatest effect.
Use Save scenario A, change an input, and compare both results side-by-side. You can also share your settings using a link.
Modelled results are estimates. Independently check decisions involving health, finances or safety.
Frequently asked questions
How is the age calculator calculated?
Age = full calendar years elapsed since birth. Enter a birth date and the date on which you want to calculate age. Leap-year birthdays are treated using the relevant calendar date where possible.
What does the age calculator example show?
With date of birth 2000-01-01, calculate as of 2026-01-01, the completed years is 26 years. Days lived: 9,497 days; Days until next birthday: 0 days.
What assumptions and limits apply?
This is an estimate based on the inputs and assumptions shown on this page, not professional advice. Check anything with financial, health or safety consequences independently.
Is my data private?
Yes. Calculations run in your browser and your numbers are not sent to a server. A share link contains the inputs you choose to share, so check it before sending it to anyone.