Date Difference Calculator
Calculate the exact number of days, weeks, months and years between any two dates. Includes business days, working hours and a full duration breakdown.
Date Difference Calculator
Calculate the duration between any two dates
The earlier date (or date of birth for age calculation)
The later date (or today’s date for age calculation)
Choose how you want the date difference broken down
Your Date Difference
Duration breakdown between your two dates
Enter a start date and end date, then click Calculate to see the exact difference in days, weeks, months and years.
Common Date Conversions
Quick reference for converting between different time units.
| Period | Days | Weeks | Approx. Months |
|---|---|---|---|
| 1 Week | 7 days | 1 week | 0.23 months |
| 1 Month (average) | 30.44 days | 4.35 weeks | 1 month |
| 3 Months (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 |
| 1 Decade | 3,652.4 days | 521.8 weeks | 120 months |
| 1 Century | 36,524.25 days | 5,217.75 weeks | 1,200 months |
Date Calculator FAQ
Everything you need to know about calculating date differences and durations.
To calculate the number of days between two dates, subtract the earlier date from the later date. For example, between 1 January and 15 January there are 14 days. This calculator does it automatically — just enter your start and end dates and it will show you the difference in days, weeks, months, years, hours, minutes and seconds.
The number of days between two dates depends on the specific dates and whether you count the start and end dates. A common year has 365 days and a leap year has 366 days. On average, a month has 30.44 days. This calculator handles all of these variations automatically, including leap years and different month lengths.
Business days (also called working days) exclude weekends (Saturday and Sunday) and optionally public holidays. To calculate business days, count only Monday through Friday between your two dates. This calculator can automatically exclude weekends and show you the number of business days between any two dates.
A leap year occurs every 4 years and has 366 days instead of 365, with an extra day on 29 February. A year is a leap year if it is divisible by 4, except for years divisible by 100 but not by 400. For example, 2000 was a leap year but 1900 was not. Leap years affect date calculations when the period spans a February in a leap year.
On average, a month has about 4.35 weeks (30.44 days ÷ 7). However, this varies: months with 31 days have 4 weeks and 3 days, months with 30 days have 4 weeks and 2 days, and February has exactly 4 weeks (or 4 weeks and 1 day in a leap year). For precise calculations, it’s better to use days rather than weeks.
To calculate age from a date of birth, subtract the birth date from today’s date. The result gives you the exact age in years, months and days. For example, if someone was born on 15 March 1990 and today is 26 June 2026, they are 36 years, 3 months and 11 days old. This calculator can do this by setting the start date as the date of birth and the end date as today.
To calculate duration in months and days, first count the complete months between the two dates, then count the remaining days. For example, from 15 January to 28 March is 2 months and 13 days (15 Jan to 15 Mar = 2 months, then 15 Mar to 28 Mar = 13 days). This calculator breaks down the difference into years, months, weeks and days automatically.
By default, this calculator counts the number of days between two dates (excluding the end date, similar to how subtraction works). You can toggle the ‘Include end date’ option to add one extra day if you want to count both the start and end dates. This is useful for scenarios like hotel bookings where you stay both the check-in and check-out nights.