How is exact age calculated?

The tool subtracts the birth date from the as-of date using calendar arithmetic: it counts completed years first, then borrows months and days where needed so February and leap years are handled correctly. A person born on 29 February ages on 28 February in non-leap years by default.

Why do age-gate thresholds differ by jurisdiction?

Different laws set different minimum ages. COPPA in the US protects children under 13, GDPR sets the digital consent age between 13 and 16 depending on the member state, most jurisdictions set 18 for gambling and contracts, and the US sets 21 for alcohol purchase.

Does this verify identity or just compute age?

It only computes age from a date you supply. It performs no identity verification and cannot confirm the date of birth is genuine. Real age-gating in production should combine this math with verified identity data.

Is my date of birth sent anywhere?

No. The calculation runs entirely in your browser using JavaScript date math. No date of birth, age, or result is transmitted or stored on any server.

Can I check age at a specific future date?

Yes. Change the as-of date to any date and the tool recomputes age and threshold pass or fail at that moment, which is handy for testing when a user will cross a 16th, 18th, or 21st birthday.

Age Verification & Date-of-Birth Calculator

Age gating is everywhere: COPPA, GDPR digital-consent rules, alcohol and gambling laws, and content ratings all hinge on a user’s exact age. This tool does the calendar-correct age math from a date of birth and then checks it against the common legal thresholds (13, 16, 18, 21), showing a clear pass or fail and how many days remain until the next milestone. It is built for developers wiring up age-gate logic and for compliance teams who need a quick, accurate check.

How it works

Naive age math (subtracting years) is wrong around birthdays and leap years. This tool uses proper calendar arithmetic:

Take the birth date and the as-of date (today by default).
Compute years = asOf.year - dob.year. If the as-of month/day is before the birth month/day, subtract 1 (the birthday has not happened yet this year).
Compute the leftover months and days by borrowing: if the day-of-month is short, borrow days from the previous month using that month’s real length; if months go negative, borrow 12 months and decrement years.

This yields an exact years / months / days breakdown that respects leap years and the differing lengths of each month.

The thresholds

Threshold	Typical legal basis
13	COPPA (US children’s online privacy)
16	GDPR digital consent (default; some states use 13-15)
18	Adulthood, gambling, contracts, most alcohol
21	US alcohol purchase

For each, the tool shows whether the computed age meets or exceeds it, and if not, the number of days until it will.

Example

A date of birth of 1 March 2008 checked as of 6 June 2026 yields 18 years, 3 months, 5 days. That passes the 13, 16, and 18 gates and fails the 21 gate, with the days-to-21 countdown shown alongside.

Notes

This is age math, not identity verification — it trusts the date you enter. In production, combine it with a verified source of date of birth. Everything runs locally; nothing you type leaves your browser.