How to Work Out Exact Ages, Days Between Dates and Meeting Times Abroad
Updated 20 October 2026 · 6 min read
Find an exact age on any date for a form, count the days to a deadline or a visa limit, and schedule calls across time zones without daylight saving mistakes.
Dates look simple until a form asks for your age on a cut-off date, a contract says “within 30 days”, or a call with a colleague abroad moves by an hour without warning. Three calculators handle these questions exactly, using real calendar dates and the same time zone data as your phone.
1. Your exact age on any date
Enter your Date of birth in the Age Calculator. It shows your age in completed years, months and days, the Total days lived and the Days until next birthday. The age is worked out as of today unless you change the As of date.
- Exams, jobs and scholarships often set an age limit on a specific date, such as “under 25 on 1 August”. Put that date in As of date rather than using today.
- Visa, insurance and pension forms usually want age in completed years: someone born on 15 March 1990 is still 36, not 37, on 1 October 2026 (36 years, 6 months and 16 days).
- Leap-year birthdays: someone born on 29 February has a real birthday only in leap years. Countries differ on whether 28 February or 1 March counts in other years.
Date of birth recorded in Bikram Sambat (BS), as on Nepali documents? Use the Age tab of the Nepali Date Converter. Subtracting 56 or 57 years by hand is often a day or more out.
2. Days between two dates
Pick a Start date and an End date in the Date Difference Calculator and it shows the gap in days, weeks, months and years. The dates can go in either order.
The count runs from the start date to the end date, so Monday to Friday is 4 days. That is right for nights in a hotel or how long ago something happened, but some rules count both the first and last day:
| Situation | Usually counts | What to do |
|---|---|---|
| Hotel stay, 1st to 5th | Nights | Use the result as it is: 4 |
| Leave from Monday to Friday | Both days | Add one: 5 |
| Visa stay, arrival to departure | Both days | Add one, then check the official rule |
| “Within 30 days of the invoice” | Days after the date | Use the result as it is |
Months vary from 28 to 31 days, so “1 month” is not a fixed number of days. When a deadline is in days, rely on the day count, which is always exact.
Counting working days? Take about 5/7 of the total, then subtract any public holidays in the range.
3. Meeting times across time zones
In the Time Zone Converter, choose the Date & time, the From time zone and the To time zone. It uses the time zone database built into your browser, so daylight saving changes are applied for the exact date you pick.
That date matters even for countries that never change their clocks. Here is a 09:00 call in New York on two dates:
| City | 15 January | 15 July |
|---|---|---|
| New York | 09:00 | 09:00 |
| London | 14:00 | 14:00 |
| Kathmandu | 19:45 | 18:45 |
| New Delhi | 19:30 | 18:30 |
| Tokyo | 23:00 | 22:00 |
| Sydney | 01:00 next day | 23:00 |
Nepal, India and Japan keep the same time all year, but the call still moves an hour for them because New York switches to daylight saving time in summer. Sydney moves by two hours, because it changes its clocks too, in the opposite season.
- Write both times in the invite, such as “09:00 New York / 19:45 Kathmandu”, not just one.
- Watch for the date changing: an evening in the Americas is already the next morning in Asia and Australia.
- For a recurring meeting, check again after March and after October or November, when most clock changes happen.
- With people in three or more zones, agree on UTC as the reference time.
Converting a Unix timestamp from a log or API? Use the Timestamp Converter instead.