Enter your date of birth to find your exact age in years, months and days — plus total days and hours lived, the weekday you were born, and a countdown to your next birthday.
🔒 Your date of birth stays in your browser — the calculation runs entirely on your device.
Complete years, months and days — calculated with real month lengths and leap years.
Your life so far in total months, weeks, days, hours and minutes.
How many days until your next birthday and the weekday you were born on.
In most of the world, age is the number of completed years since birth, incrementing on the anniversary. Someone born on 1 August 2000 turns 26 on 1 August 2026 and is 25 the day before. This is the East Asian reckoning's counterpart — the traditional Korean system counted a newborn as one and added a year at each new year, so someone born in December was two after a few weeks. South Korea standardised on international reckoning in June 2023, though the traditional count persists socially.
The 29 February case has no universal answer. Someone born on a leap day has a legal birthday of 28 February in some jurisdictions and 1 March in others, which matters for the precise moment a legal threshold is crossed. In practice most systems use 28 February in non-leap years.
For ages expressed in years, months and days, the order of operations matters. Subtracting years first, then months, then days, gives a different result from computing total days and decomposing — because months vary in length, there is no single correct decomposition, and different tools legitimately differ by a day.
Precision matters more than it might seem. Legal thresholds — voting, driving, alcohol, contracts, retirement eligibility — turn on a specific date, and being a day short is decisive. School year placement is usually determined by age on a cutoff date rather than at enrolment, so a birthday days either side of it changes which cohort a child joins.
In medicine, age drives drug dosing, growth chart percentiles and screening eligibility, and for infants it is counted in days or weeks rather than years because development is rapid. Paediatric practice also distinguishes chronological age from corrected age for babies born preterm, subtracting the weeks of prematurity when assessing milestones — a distinction that avoids unnecessary alarm about development.
Insurance and pension calculations frequently use age at next birthday or age nearest birthday rather than completed age, which can shift a premium band. If a figure from this tool disagrees with an official one, a differing convention is the likely reason rather than an arithmetic error.
Life expectancy is the most misread age statistic. A figure of 40 for a historical population does not mean people typically died at 40 — it is an average dragged down heavily by infant mortality. Someone in a pre-modern society who survived to 20 could often expect to reach their sixties. Period life expectancy at birth and remaining life expectancy at a given age are quite different measures.
Age cohorts also behave differently from age groups. A statement about "people in their twenties" describes whoever occupies that band now; a statement about a birth cohort follows the same people over time. Confusing the two produces claims about generational change that are really about ageing.
This tool computes calendar arithmetic only. It is not a health, legal or financial instrument, and where a threshold has consequences — a legal age, a benefit eligibility date, a medical dosing decision — confirm against the governing rules for your jurisdiction rather than relying on a calculated figure.
We subtract your birth date from the chosen date, accounting for the real number of days in each month and for leap years, to give complete years, months and days.
Yes — change the "Age on" date to any date to see how old you were or will be then.
The result shows the weekday of your birth date plus a countdown to your next birthday.
Completely free, no sign-up, and everything runs locally in your browser.
It varies by jurisdiction — some treat 28 February as the legal birthday in non-leap years, others 1 March. Most software uses 28 February.
Because months vary in length there is no single correct decomposition. Subtracting years, then months, then days gives a different remainder from computing total days and splitting them, and both are defensible.