Runs in your browser · nothing is uploaded
Age & Date Calculator
Work out an exact age, count the days between two dates, or find the date a number of days, weeks or months from now. Results update as you type.
How the calculations work
Age
Whole years since you were born, then whole months since your last birthday, then the remaining days. Totals in months, weeks and days are shown too, along with how long until your next birthday.
Days between
The number of days from the start date to the end date, also shown as weeks and as years, months and days, with the split between weekdays and weekend days.
Add / subtract
Years and months are added first, then weeks and days. When a month is shorter, the date moves to its last day — 31 January plus one month is 28 or 29 February.
Useful examples
- Notice period: add 30 days or 1 month to your resignation date to find your last day.
- Working-day deadline: add 10 weekdays to today, skipping weekends.
- Countdown: days between today and a wedding, exam, holiday or due date.
- Eligibility: check someone's exact age on a cut-off date for school, a visa or a competition.
Frequently asked questions
How is my exact age calculated?+
It counts the whole years since your date of birth, then the whole months since your last birthday, then the days left over. Someone born on 15 June 1990 is 36 years, 3 months and 20 days old on 5 October 2026.
How are birthdays on 29 February handled?+
In years that aren't leap years, this calculator counts the birthday on 28 February. Conventions differ: some people celebrate on 1 March, and in some countries, such as the UK, 1 March is the legal birthday for things like coming of age.
Does “days between” include the start and end dates?+
By default it counts the days from the start date up to the end date, like nights in a hotel stay: Monday to Friday is 4 days. Tick “Include the end date” to count both, which makes Monday to Friday 5 days.
How do you count months when the dates fall at the end of a month?+
Adding a month to 31 January gives 28 February (29 in a leap year), because February has no 31st. In the same way, 31 January to 28 February counts as one whole month.
Can I count only working days?+
Yes. “Days between” shows the number of weekdays (Monday to Friday), and “Add / subtract” can count weekdays only, for deadlines like “10 working days from today”. Public holidays aren't excluded, because they differ by country and region.
Which dates can I use?+
Any date from the year 1 to 9999, using the modern (Gregorian) calendar throughout. Dates are treated as whole calendar days, so time zones and daylight saving changes don't affect the results.
Is my date of birth stored or sent anywhere?+
No. Everything is calculated in your browser and nothing is saved or uploaded.