Age Calculator

What the Age Calculator does

Forms ask your age "as on" a fixed date, and months of different lengths make that awkward to count by hand. Pick your date of birth and the cut-off date and this tool gives the age as years, months and days, the way people usually say it.

It also shows the total days since birth and the date of your next birthday. Preset buttons fill in the common cut-offs, and an optional box checks the born-between dates a notice prints. For the full method, see Age on a cut-off date.

How it works

It adds whole months to your date of birth until one more month would pass the cut-off date, then counts the days left over. That gives full years, then months, then days, the way a birthday is counted. A birthday on the 31st falls back to the last day of a shorter month, and 29 February falls back to 28 February in other years.

It also counts the plain days between the two dates and shows your next birthday on or after the cut-off. If you enter born-between dates, it checks your date of birth against them with both ends included.

Methodology

1. Step 1. Enter a date of birth and the cut-off date, or pick a preset: today, 1 Aug 2026, 31 Mar 2026 or 1 Jan 2027.
2. Step 2. Count the whole months from birth to the cut-off, stepping back one if the last month would pass it.
3. Step 3. Split the months into years and months; the days left over are the days.
4. Step 4. Count the total days and find the next birthday on or after the cut-off.
5. Step 5. If you entered born-between dates, test your date of birth against them, both ends included.

How the age is counted

This matches the convention of Python's dateutil relativedelta. Some calculators borrow the previous month's length instead; around month ends and on 29 February the two methods can differ by a day.

Assumptions

• Dates are calendar dates handled in UTC, so your device's time zone can't shift the answer by a day.
• The calendar takes care of different month lengths and leap years.
• The cut-off date starts at 1 August 2026; press Today or another preset to change it.
• A month runs from one day of the month to the same day next month, so months vary in length.

Technical details

Standards and references

• Gregorian calendar: the basis for the count, including the leap-year rule that keeps the calendar year in step with the seasons.
• Calendar age convention: full years, then leftover months, then leftover days, borrowing when a subtraction goes negative. Birthdays and legal ages are normally stated this way.

Accuracy and limits

The years, months and days come from counting whole months forward from the date of birth, then the leftover days. A birthday that does not exist in the target month (the 31st, or 29 February) is moved to that month's last day.

Plain arithmetic and some official rules differ by one day. The Supreme Court reading quoted in CBDT Circular 28/2016 says you attain an age on the day before your birthday, and KVS counts a 1 April child as 6 on 31 March. The tool shows the arithmetic and flags that case; the notice decides.

Total days is the exact whole-day difference between the two dates, so every leap day in the span is included.

It works to the day, not the hour. Hours, minutes and time-zone shifts within a day are not tracked.

Real-world uses

When it fits, and when it doesn't

For a gap in hours and minutes, use a time-duration calculator. For a plain day count, a date-difference calculator works too.

Frequently asked questions

References

• UPSC, Civil Services Examination 2026 notice, Age Limits
• KVS Admission Guidelines 2026-27
• dateutil relativedelta documentation
• Gregorian calendar — Wikipedia
• Leap year — Wikipedia

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