About this calculator
The Age Calculator calculates exact age from a date of birth to today or to another selected date. It shows years, months, days, total days, total weeks, and next-birthday information. It is useful for everyday age checks, school year planning, age eligibility, forms, anniversaries, and comparing dates without manually counting across leap years and month lengths.
Age calculation method
The calculator compares the birth date with the target date, counts complete calendar years first, then complete months, then remaining days. It also calculates total elapsed days and weeks for users who need a pure duration.
- age years = completed calendar years between birth date and target date
- age months = completed months after full years are removed
- age days = remaining days after years and months are removed
- total days = target date - birth date
How to use the age calculator
- Enter the date of birth.
- Use today as the target date or choose another date.
- Review exact age in years, months, and days.
- Use total days or weeks if you need elapsed time rather than calendar age.
- Check next birthday information for planning.
- For eligibility rules, read the official rule that defines the age cut-off.
Worked examples
Exact age today
Input: Date of birth 10 March 2000, target date 19 June 2026
Calculation: Count completed years, then months and days to the target date
Result: The person is 26 years, 3 months, and 9 days old.
Age on a future date
Input: Date of birth 1 September 2015, target date 31 August 2026
Calculation: Compare the birth date with the selected future date
Result: The calculator shows age just before the next birthday.
Calendar age vs total days
Calendar age is normally written as years, months, and days. Total days is a pure elapsed duration. Both can be correct, but they answer different questions. Forms and eligibility rules usually care about calendar age, while data analysis may care about total days.
Age eligibility checks
| Use case | What to check | Important caution |
|---|---|---|
| School or course age | Age on a specific cut-off date | Rules vary by institution |
| Employment or benefits | Age on an entitlement date | Check GOV.UK or employer policy |
| Health or pregnancy tools | Age-related context | Use clinical guidance where relevant |
| Anniversaries | Years since a date | A years-between calculator may also help |
Leap years and birthdays
Leap years matter because February can have 29 days. People born on 29 February may have official birthday handling that depends on the context, country, or organisation. The calculator provides date arithmetic, not a legal interpretation of leap-day rules.
Common mistakes and edge cases
- A target date before the birth date is not a valid age check.
- Leap-day birthdays may be handled differently by organisations.
- Eligibility rules may use age at the start or end of a period.
- Time of birth is not included.
- Age in total days is not the same as calendar age.
Limitations and cautions
This calculator is for general date arithmetic. It does not decide legal eligibility, school admission, employment rights, benefit entitlement, immigration status, or medical suitability.
- Check official rules for age cut-offs.
- Use the exact target date required by the form or policy.
- Do not use it as medical or legal advice.
Frequently asked questions
How do I calculate exact age?
Enter the date of birth and the target date. The calculator counts complete years, months, and days.
Can I calculate age on a future date?
Yes. Choose a future target date to see age on that date.
Does it handle leap years?
Yes. The date arithmetic handles leap years and different month lengths.
What is total age in days?
It is the total number of calendar days between the birth date and target date.
Can this decide eligibility?
No. It can calculate age, but official rules decide eligibility.
Related calculators
- date-add-subtract-calculator
- age-difference-calculator
- day-of-week-calculator
- years-between-dates-calculator