Everyday tool
Age and Date Difference Calculator
Work out an exact age, the days between two dates, or add and subtract days, weeks, months and years, with an optional business-days mode and holidays.
Free, no sign-up. Runs in your browser; nothing is uploaded.
Dates
Result
34 years, 2 months, 22 days
Next birthday: in 282 days (2027-08-15, a Sunday).
How to use the age and date difference calculator
Three date calculators in one
Dates look simple until months of different lengths, leap years and weekends get involved. This tool handles all of that so you can trust the answer for forms, contracts, HR and planning.
Age
Enter a date of birth and, if you wish, a different "age on" date (it defaults to today). You get the age in years, months and days, plus the total days, weeks and months, the weekday you were born on and how many days remain until the next birthday. Leap-day birthdays are handled: in non-leap years the birthday is counted on 28 February.
Days between two dates
Pick a start and end date. The result shows the calendar difference as years, months and days, the total number of days, weeks and days, hours and the number of business days. Tick the inclusive option to count both the first and the last day. If you paste holidays in the box, they are removed from the business day count. The order of the dates does not matter; if the end is before the start, the gap is still shown as a positive number.
Add or subtract time
Choose a start date, a direction, an amount and a unit: days, weeks, months or years. The answer includes the weekday. For days you can switch on business days only to skip weekends and your listed holidays, which is useful for delivery estimates, notice periods and payment terms.
Good to know
- Everything is calculated in UTC calendar dates, so daylight saving time cannot move a result by a day.
- Months are calendar months, not 30 days. Adding one month to 30 January lands on 28 or 29 February.
- Business days here are a simple Monday-to-Friday count. Regional weekends and half days are not modelled.
- For legal or payroll deadlines, confirm the rules that apply to you, such as whether the first day counts.
Use the copy button to paste the result into an email or form. Nothing you enter leaves your device.
Frequently asked questions
How is the exact age worked out?
The tool counts whole years and months from the birth date, then the leftover days. If you were born on 31 January, one month later is clamped to the end of February, so the day count never goes negative.
Does the day count include the end date?
By default no: 1 January to 2 January is one day. Tick "count the end date too" for inclusive counting, which is common for leave, contracts and hotel nights in some countries.
How are business days counted?
Saturdays and Sundays are skipped. You can also paste public holidays as yyyy-mm-dd dates and they are skipped as well. Weekends are fixed to Saturday and Sunday in this version.
Why does adding one month to 31 January give 28 February?
February has no 31st, so the date is clamped to the last day of the month. The same rule applies to leap years and to 30-day months.
Is my date of birth stored anywhere?
No. All calculation happens in your browser and nothing is saved or uploaded.