How to Calculate Age in Months: Formula, Steps & Examples
Learn how to calculate Age in Months — the formula explained step by step, with worked examples and a free calculator to check your answer.
Age in Months Calculator
Verified formula Updated Jun 2026 Private — runs on your device
Verified formula
Private
Age in months
65.4
- Age in days
- 1,991
For general information only — not financial, tax, legal or medical advice. Verify before you rely on it.
How to use the Age in Months Calculator
The Age in Months Calculator works out your age in months, along with 1 related figure in an instant. Enter date of birth and as of date and the result updates as you type — it is free, needs no sign-up, and runs entirely in your browser so your figures stay private.
- Pick the date of birth.
- Pick the as of date.
- Read off your age in months, together with age in days — the calculator updates automatically, with no button to press.
Worked example
For example, with date of birth of 1990-01-01 and as of date of 1995-06-15, the age in months is 65.4.
| Date of birth | 1990-01-01 |
|---|---|
| As of date | 1995-06-15 |
| Age in months | 65.4 |
|---|---|
| Age in days | 1,991 |
Results are estimates for educational use, not professional advice.
Frequently asked questions
Take the days between the two dates and divide by 30.44, the average month length. 1990-01-01 to 1995-06-15 is about 65 months.
It is the average month length over a year (365.25 ÷ 12), which smooths out months of different lengths.
Yes. Parents and doctors often track an infant's age in months, which this makes easy from any two dates.
No. The calculator uses the absolute difference, so the result is positive either way.
Pick the date of birth. Pick the as of date. Read off your age in months, together with age in days — the calculator updates automatically, with no button to press.