Age Calculator

Pick a date of birth to see the exact age in years, months and days, the days until the next birthday, and the day of the week you were born. It works in your browser and nothing is uploaded.

Date of birth

Age on

Pick a date of birth and your exact age shows here.

Uses a standard calendar calculation. For legal deadlines or official decisions, check the rules that apply to you. Full disclaimer and terms of use.

How the age calculator works

Your age is the time that has passed since you were born. The calculator counts how many full years fit between your date of birth and the date you choose, then how many full months are left, then the remaining days. The date of the answer defaults to today, so it is always up to date when you open the page.

What you get

Exact age in years, months and days.
Total months, weeks, days and hours lived.
The day of the week you were born on.
Your next birthday, how many days away it is, and the age you will turn.

When an exact age matters

School and sports entry, where children must reach an age by a cut-off date.
Job, visa, licence and benefit applications that ask for your age on a given day.
Retirement, insurance and pension planning.
Fun facts such as how many days old you are, or the weekday of your birth.

How old is that in days, weeks and months?

A year averages 365.25 days once leap years are counted, so these totals are close to what the calculator shows for someone whose birthday is today.

Age	Months	Weeks (about)	Days (about)
10 years	120	522	3,652
16 years	192	835	5,844
18 years	216	939	6,574
21 years	252	1,096	7,670
30 years	360	1,565	10,958
40 years	480	2,087	14,610
50 years	600	2,609	18,263
65 years	780	3,392	23,741
100 years	1,200	5,218	36,525

Leap years and month lengths

Months have 28 to 31 days, so counting whole months from a date like the 31st needs a rule. When a month is too short, the calculator uses its last day: one month after 31 January is 28 February (29 in a leap year). People born on 29 February celebrate on 1 March in years without a leap day, which is the rule used for the birthday countdown here.

How to work out your age by hand

Subtract your birth year from the year you want the age on. If your birthday has not happened yet in that year, subtract one more. For example, someone born on 15 March 1990 is 36 on 20 May 2026 (2026 − 1990 = 36, and the birthday has passed), but was only 35 on 10 February 2026. For months and days, count forward from the last birthday.

Different ways of counting age

International (Western) age: your age goes up on your birthday. This is what the calculator shows and what most countries use for legal purposes.
East Asian age counting: a baby is 1 at birth and everyone gains a year on New Year. South Korea moved to the international system for most legal and administrative uses in June 2023.
Completed versus current year of life: when a form asks for your age "next birthday", it wants your age plus one.

How to calculate age in Excel or Google Sheets

With a date of birth in A1, use =DATEDIF(A1,TODAY(),"Y") for whole years, =DATEDIF(A1,TODAY(),"YM") for the extra months and =DATEDIF(A1,TODAY(),"MD") for the extra days. Combine them with & to build a sentence like the one this page gives you.

How to use the Age Calculator tool

Choose the date of birth in the first box.
Leave "Age on" as today, or pick another date to find the age on that day.
Read the exact age, the totals in months, weeks, days and hours, and the next birthday.

Frequently asked questions

How is age calculated in years, months and days?

The calculator counts the whole years and months from the date of birth, then the days that are left over. From 15 March 1990 to 20 May 2026 that is 36 years, 2 months and 5 days.

Can I find my age on a past or future date?

Yes. Change the "Age on" date to any date, for example a school cut-off date, a job application deadline or a future birthday.

What happens if I was born on 29 February?

In years that have no 29 February, this calculator treats 1 March as the birthday. Some places use 28 February instead, so check the rule that applies to you for legal purposes.

Why do the totals in days and hours differ from other sites?

Total days count every calendar day between the two dates. Hours are the total days multiplied by 24, so they do not include the time of day you were born.

How do I calculate my age from my birth year?

Subtract your birth year from the current year, then subtract one more if your birthday has not happened yet this year. For an exact age in months and days, enter your full date of birth in the calculator.

How many days until my next birthday?

Enter your date of birth and the calculator shows your next birthday, how many days away it is and the age you will turn. It always counts from today unless you change the "Age on" date.

How do I find the age difference between two people?

Enter the older person's date of birth and set "Age on" to the younger person's date of birth. The result is the age gap in years, months and days. You can also use the Date Difference Calculator with the two birth dates.

Is my date of birth stored or sent anywhere?

No. The calculation happens inside your browser, so the date you pick never leaves your device.

How many days old am I?

Enter your date of birth and the calculator shows your age in total days, weeks, months and hours. As a guide, someone who has just turned 18 has lived about 6,574 days, and a 30-year-old about 10,958 days.

Last reviewed: October 22, 2026.