Date Difference Calculator
Calculate the exact difference between two dates in years, months, weeks, days, hours, and minutes. See weekdays vs weekends.
Select two dates to instantly see the difference in years, months, weeks, days, hours, and minutes, plus weekday/weekend breakdown.
Why Date Calculations Are Harder Than They Look
Counting days between dates sounds trivial until you actually think about it. Months have 28, 29, 30, or 31 days. Years are 365 days — except leap years, which are 366. And "one month from January 31st" doesn't neatly land on February 31st because that date doesn't exist.
This calculator handles all of that complexity. It uses the date-fns library to correctly compute differences across month boundaries, leap years, and varying month lengths. The result breaks down into years, months, weeks, and remaining days — plus total counts in each unit separately for when you need a single number.
It also splits the count into weekdays and weekends, which is useful for project planning and business calculations. If you need only business days, use our dedicated Business Days Calculator.
Quick Reference: Days in Each Month
| Month | Days | Month | Days |
|---|---|---|---|
| January | 31 | July | 31 |
| February | 28/29 | August | 31 |
| March | 31 | September | 30 |
| April | 30 | October | 31 |
| May | 31 | November | 30 |
| June | 30 | December | 31 |
What this means for you: February is the wildcard — 28 days normally, 29 in leap years (every 4 years, except centuries not divisible by 400). The next leap year is 2028.
When You Need Date Differences
Age Verification
Calculate exact age in years, months, and days from a date of birth. Useful for forms, legal age checks, and milestone tracking.
Contract Duration
How long has a lease been running? When does the notice period end? Date differences remove the guesswork from legal timelines.
Travel Planning
Knowing the exact number of nights between departure and return dates helps with hotel bookings, travel insurance, and itinerary planning.
Fitness & Health Tracking
Track how many days you've been on a programme, how long until a race, or the gap between medical appointments.
Common Date Difference Calculations
| Scenario | Typical Duration | Watch For |
|---|---|---|
| UK notice period (1 month) | 28-31 days | Calendar month, not 30 days |
| Probation period (3 months) | 89-92 days | Check if it's calendar or working days |
| Standard pregnancy | 280 days (40 weeks) | Counted from last menstrual period |
| UK passport renewal | 3-10 weeks | Longer during peak periods |
| Cooling-off period (online) | 14 days | Calendar days from delivery date |
Related Tools
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Age Calculator
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Unix Timestamp Converter
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How to use this tool
Enter the start date
Enter the end date
Click Calculate to see the full breakdown
Common uses
- Calculating exact age or time elapsed since a date
- Determining contract and lease durations
- Planning travel with accurate day counts
- Tracking time between medical appointments or milestones
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