Age Calculator

Age is calculated from your date of birth to today (or a custom end date), accounting for varying month lengths and leap years so the result is precise. Everything runs locally in your browser — your inputs are not uploaded to produce the result.

It calculates using calendar dates, so it accounts for different month lengths and leap years. The result is exact for the dates you enter. Choose a custom end date instead of today to find how old someone was (or will be) on that day.

Along with your exact age, you’ll see how many days remain until your next birthday. Tweak the inputs above to compare options, then copy or note the result you need.

Years, months, and days are counted on the civil calendar, not as “365 × years”. A child born on 31 January is not “one month old” on 31 February — that date does not exist, so the tool rolls with real month lengths. The same logic applies at the end of February in leap and non-leap years.

Use a custom end date for “how old were they on this wedding day?” or “how old will I be on this date?”. The next-birthday figure is measured from that end date, not necessarily from today. For a raw total of days lived, the Age in Days calculator is the clearer view.