Date Duration Calculator
Calculate the number of days, weeks, months, or years between any two dates. Add or subtract days, calculate exact age, and find business days — all instantly.
Date Duration Calculator
Calculate date differences, add/subtract days, and more
The earlier date in your range
The later date in your range
Enter your date of birth to calculate your exact age
Leave blank to calculate age as of today
Your Date Calculation
Duration, breakdown, and key facts
Select a calculation type, enter your dates, then click Calculate to see the results.
Date Duration Benchmarks
Common date durations and their equivalents in different units.
| Duration | Days | Weeks | Months (approx) |
|---|---|---|---|
| 1 Week | 7 days | 1 week | 0.23 months |
| 1 Month | 30.44 days | 4.35 weeks | 1 month |
| 1 Quarter | 91.31 days | 13.04 weeks | 3 months |
| 6 Months | 182.63 days | 26.09 weeks | 6 months |
| 1 Year (common) | 365 days | 52.14 weeks | 12 months |
| 1 Year (leap) | 366 days | 52.29 weeks | 12 months |
| 100 Days | 100 days | 14.29 weeks | 3.29 months |
| 1000 Days | 1000 days | 142.86 weeks | 32.85 months |
Date Calculator FAQ
Everything you need to know about calculating date durations and differences.
To calculate the number of days between two dates, subtract the earlier date from the later date. For example, between 1 January 2026 and 15 March 2026: January has 31 days (30 remaining after Jan 1), February has 28 days (2026 is not a leap year), plus 15 days in March = 30 + 28 + 15 = 73 days. This calculator handles all the math automatically, including leap years and varying month lengths.
A common year has 365 days. A leap year has 366 days, with an extra day added to February (29 February). Leap years occur every 4 years, except for years divisible by 100 but not by 400. For example, 2000 was a leap year, but 1900 was not. The next leap years are 2028, 2032, 2036, and 2040.
To calculate your exact age, subtract your birth date from today’s date. For example, if you were born on 15 June 1990 and today is 26 June 2026: you are 36 years, 0 months, and 11 days old. The calculation accounts for leap years and the exact number of days in each month. This calculator provides your age in years, months, weeks, days, hours, and even minutes.
Business days (also called working days) are Monday through Friday, excluding weekends (Saturday and Sunday) and public holidays. To calculate business days between two dates, count only weekdays. For example, between Monday 1 June and Friday 5 June 2026, there are 5 business days. Between Monday 1 June and Monday 8 June, there are also 5 business days (the weekend is excluded). This calculator can exclude weekends and optionally UK bank holidays.
To add days to a date, simply add the number of days to the day value and adjust for month/year overflow. For example, adding 45 days to 1 March 2026: March has 31 days, so 45 − 31 = 14, giving us 14 April 2026. This calculator handles all the complexity automatically, including leap years, month-end dates, and year boundaries. You can also add weeks, months, or years.
On average, a month has about 4.345 weeks (52 weeks ÷ 12 months). However, individual months vary: a 28-day month (February in non-leap years) has exactly 4 weeks, a 30-day month has 4 weeks and 2 days, and a 31-day month has 4 weeks and 3 days. Over a full year, there are 365 days = 52 weeks and 1 day (or 52 weeks and 2 days in a leap year).
Date durations can be expressed in multiple formats: total days, weeks and days, months and days, or years, months, and days. For example, 400 days equals: 400 days, or 57 weeks and 1 day, or approximately 13 months and 4 days, or 1 year, 1 month, and 5 days. This calculator shows all formats simultaneously so you can choose the most useful one.
No, 2026 is not a leap year. Leap years are divisible by 4, but 2026 ÷ 4 = 506.5, which is not a whole number. The most recent leap year was 2024, and the next leap year will be 2028. In 2026, February has 28 days and the year has 365 days total.