Find your exact age in years, months & days. Plus days lived, next birthday countdown, and the day you were born.
Enter your date of birth and the date to calculate age on
Your heart beats about 100,000 times per day. In a lifetime, that's over 2.5 billion beats.
We sleep about 1/3 of our lives. A 30-year-old has slept roughly 10 years.
Earth travels 940 million km around the sun each year. Every birthday = one full orbit.
Your brain generates about 70,000 thoughts per day - that's 25 million per year.
Most people work out age by subtracting one year from another, which is fine for a rough answer and wrong for anything official. Real age is calendar arithmetic, not division. You count whole years from the date of birth to the same date in the current year, then whole months from that anniversary, then the leftover days. The reason this matters is that months are not equal: a gap that crosses February behaves differently from one that crosses July, and dividing total days by 365 quietly drifts by roughly one day every four years.
This tool walks the calendar the way a registrar does. It finds how many complete years have passed, borrows a month when the day-of-month has not yet been reached, and borrows the correct number of days for the specific month being borrowed from. That is why the result can read something like 34 years, 7 months and 19 days rather than a decimal.
Take a birth date of 12 March 1990 and a target date of 5 August 2026. The last birthday was 12 March 2026, so 36 complete years have passed. From 12 March to 12 July is four complete months. From 12 July to 5 August is not a complete month, so we borrow: July has 31 days, giving 24 days from 12 July to 5 August. The exact age is 36 years, 4 months and 24 days. A naive calculation of total days divided by 365 would return 36.4, which is true but useless on a form.
A leap year adds 29 February every four years, skipping century years that are not divisible by 400. The year 2000 was a leap year; 1900 and 2100 are not. For age calculation this creates two practical wrinkles.
The first is people born on 29 February. In non-leap years there is no such date, so the birthday has to be treated as either 28 February or 1 March depending on the rule being applied. Different institutions genuinely disagree. Many government and insurance systems treat 1 March as the effective birthday in common years, while some school and legal contexts use 28 February so that the person does not appear a day younger than peers born on 28 February. If you were born on 29 February and a deadline is close, check which convention the specific institution uses rather than assuming.
The second wrinkle is that any age measured in days will be one day longer than expected if the interval spans a 29 February. This is invisible in a years-months-days result but shows up immediately in a total-days figure, which is why the two views can look inconsistent when they are both correct.
An approximate age is fine socially and useless administratively. These are the situations where the day matters:
These two conventions produce different numbers for the same person and both are legitimate. Age last birthday is your completed age, the number you would say out loud. Age nearest birthday rounds to whichever birthday is closer, so someone who is 34 years and 8 months old is 34 by the first convention and 35 by the second. Insurance underwriting frequently uses age nearest birthday because it prices risk more smoothly across the year. When a quote comes back a year older than you expected, this is usually why.
Being honest about limits is more useful than pretending there are none. This tool works on calendar dates only. It does not use your time of birth, so it cannot resolve the handful of cases where the hour matters, such as twins born either side of midnight. It uses your device's local date as the default target, so if you are travelling across time zones near midnight the default may be a day off; set the target date manually in that case. It also assumes the Gregorian calendar throughout. Dates before the local adoption of the Gregorian calendar, or dates recorded in another calendar system, need conversion first.
A date of birth is one of the most reusable pieces of personal data there is. Combined with a name it is enough to open accounts, pass telephone identity checks and reset passwords, which is exactly why it sits on so many verification forms. There is no technical reason for a date of birth to travel to a server just to perform subtraction, so on this page it does not. The arithmetic runs in your browser using JavaScript that is already loaded with the page. Nothing you type is transmitted, stored, logged or attached to an analytics event, and you can confirm that by opening your browser's network tab and watching it stay silent while you calculate. The page also works offline once loaded, which is a side effect of the same design.
Enter your date of birth and the date you want to measure to. The calculator counts complete years first, then complete months from your last birthday, then the remaining days, borrowing the correct number of days for the specific month involved. This is the same method used on official forms, and it is more accurate than dividing total days by 365.
Conventions differ. Many government and insurance systems treat 1 March as the effective birthday in non-leap years, while some school and legal contexts use 28 February. If a deadline falls close to the boundary, check which rule the specific institution applies rather than assuming.
Age last birthday is your completed age, the number you would normally say. Age nearest birthday rounds to whichever birthday is closer, so at 34 years and 8 months you are 34 by the first convention and 35 by the second. Life insurers often use age nearest birthday, which is why a quote can come back a year older than expected.
Yes. Set the target date to any date you like. This is what you need when a form asks for your age as on a specific reckoning date, such as a school admission cut-off or an exam eligibility date, rather than your age today.
Yes. It walks the real calendar, so any 29 February inside the interval is counted. This is why a total-days figure can be a day longer than a rough estimate based on 365-day years.
No. The entire calculation runs in your browser on your own device. Your date of birth is never transmitted to a server, stored, or logged, and the page continues to work with your network disconnected.
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