Age Calculator
Work out how old you are in years, months and days, and how many days are left until your birthday.
Age in years
36
July 15, 1990 · October 6, 2026
Plus months
2
Plus days
21
Age in months
434
Age in weeks
1,890
Age in days
13,232
Days until the next birthday
282
Next birthday
July 15, 2027
Please note: The result is an estimate and has been rounded. Actual costs and values may differ, and no rights can be derived from this calculation.
How this number is calculated
The blocks use your input. Change a value above and they update with it.
Step 1 · Whole months
Step 2 · Age in years
Step 3 · Plus months
Step 4 · Last whole month ended on
Step 5 · Plus days
Step 6 · Age in days
Step 7 · Last birthday
Step 8 · Days until the next birthday
Step 9 · Next birthday
How the calculation works
Enter a date of birth and the date you want to know the age on. You see the age in years, months and days, also as a total number of months, weeks and days, and how many days are left until the next birthday.
You turn a year older on your birthday. The calculator first counts the whole months since birth: a month is complete when the same day of the month comes round again. Twelve whole months make a year; the months and days left over are added. If you were born on 29 February, your birthday counts on 1 March in years without 29 February. The total number of days is the difference between the two dates.
Formula
Months = (year − birth year) × 12 + (month − birth month), minus 1 if the day of the birth month has not been reached yet. Age = months ÷ 12, rounded down. Days = date − date of birth. Weeks = days ÷ 7, rounded down.
Assumptions
- You turn a year older on the day of your birthday itself.
- Born on 29 February? In a year without 29 February your birthday counts on 1 March.
- A month is complete on the same day of the month. If that day does not exist, such as 31 April, the 1st of the following month counts.
- If today is your birthday, there are 0 days until your birthday.
- Only whole days count: the time of birth and time zones are left out.
Example calculations
The button fills in the calculator above, so you can carry on from there.
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Age on your first day at work
Age in years
22
Date of birth March 12, 2004 · Age on September 1, 2026
Born on 12 March 2004, first day at work on 1 September 2026.
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Age of a baby
Age in years
0
Date of birth March 20, 2026 · Age on October 4, 2026
Born on 20 March 2026: 6 months and 14 days old on 4 October.
-
Born on 29 February
Age in years
19
Date of birth February 29, 2008 · Age on March 1, 2027
Born on 29 February 2008: in 2027 the birthday falls on 1 March.
Frequently asked questions
How do I calculate my age?
Subtract your year of birth from the current year. If you have not had your birthday yet this year, subtract 1. Born on 15 July 1990? On 4 October 2026 you are 2026 − 1990 = 36, because your birthday has already passed.
How old am I in days?
That is the number of days from your date of birth to today, including every leap day. Someone born on 15 July 1990 is exactly 13,230 days old on 4 October 2026. Enter your own date of birth and the calculator works it out.
When is my birthday if I was born on 29 February?
In a leap year simply on 29 February. In other years this calculator uses 1 March, because only then has the whole of 28 February passed. Official rules can differ: some countries and organisations use 28 February instead.
How many days until my birthday?
Enter your date of birth and set ‘Age on’ to today's date. The calculator shows how many days are left and on which date your next birthday falls. If today is your birthday, it shows 0.
How do I work out a baby's age in months?
Count the whole months since birth. A baby born on 20 March is 1 month old on 20 April and 6 months and 14 days old on 4 October. The calculator also shows the total number of weeks, which is handy in the first year.
Can I calculate my age on another date?
Yes. Enter any date under ‘Age on’, in the past or in the future. That way you can see how old you were on your wedding day, or how old you will be on your first day at a new job.
Sources and checks
Sources
How we check it
This calculator has 21 fixed checks: 17 calculations with a result that is fixed in advance, and 4 cases of invalid input that must be rejected. They all run automatically every time we publish; if one fails, the calculator does not go live.
See the calculations
- Date of birth July 15, 1990 · Age on October 4, 2026 → Age in years 36
- Date of birth March 12, 2004 · Age on September 1, 2026 → Age in years 22
- Date of birth March 20, 2026 · Age on October 4, 2026 → Age in years 0
- Date of birth February 29, 2008 · Age on March 1, 2027 → Age in years 19
- Date of birth February 29, 2000 · Age on February 28, 2027 → Age in years 26
- Date of birth February 29, 2000 · Age on February 29, 2028 → Age in years 28
- Date of birth February 29, 2000 · Age on February 28, 2028 → Age in years 27
- Date of birth October 4, 1990 · Age on October 4, 2026 → Age in years 36
- Date of birth October 5, 1990 · Age on October 4, 2026 → Age in years 35
- Date of birth October 4, 2026 · Age on October 4, 2026 → Age in years 0
Changes
- : Sources added and content reviewed.
- : First version.
Last reviewed: · How we build and check our calculators
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