Age Calculator
Exact age counts from zero at birth and adds a year on each birthday — the definition used on passports, contracts and medical records almost everywhere. Enter a date of birth and this tool returns the completed years as of today, or as of any reference date you choose, along with the days remaining until the next birthday.
How to use
- Enter the date of birth.
- Leave the reference date blank for today, or set it to the date a form or rule actually applies from.
- Read the completed age and the countdown to the next birthday.
- For paperwork, use the submission or effective date as the reference — not the day you happen to be filling it in.
When you actually need this
- Filling in a visa, insurance or employment form that asks for age in completed years.
- Checking an eligibility cut-off that is defined as of a specific date.
- Working out age at retirement, pension start or policy maturity.
- Counting a young child's age in months for vaccination or school-entry schedules.
Why the reference date matters
Age rules are almost always written as "age on a given date", not "age today", and the two differ for anyone whose birthday falls between the two dates. Application deadlines, examination cut-offs and benefit start dates are the usual places this bites. A separate wrinkle applies to people born on 29 February: in non-leap years most legal systems treat the birthday as falling on 1 March, though some contracts specify 28 February instead, so it is worth checking the wording rather than assuming.
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FAQ
What formula does Age Calculator use?
It uses the standard published formula for this calculation, applied exactly as written with no rounding until the final result. The inputs you provide are the only variables — there are no hidden assumptions or regional adjustments.
How accurate is the result from Age Calculator?
The arithmetic is exact to the precision your browser supports. Accuracy in practice depends on your inputs: an estimate built on rounded figures will itself be an estimate, so enter the most precise values you have.
Can I use this for official or financial decisions?
Treat the output as a well-calculated estimate rather than professional advice. For medical, tax, legal or lending decisions, confirm the figure with a qualified professional or the institution involved before acting on it.