Date Difference Calculator (Days Between Dates)
Count the exact time between two dates — in days, weeks, months and years. Perfect for deadlines, countdowns, project timelines, notice periods, visa stays and "how many days until" questions.
How to use this calculator
- Pick the start date and end date — order doesn't matter, it sorts them for you.
- Choose whether to count the end date: exclude it for pure differences, include it for stays and event durations.
- Press Calculate to see total days, the calendar breakdown, weeks and weekdays.
Formula used
The calendar breakdown (years, months, days) borrows across month boundaries like age calculation. The weekday count excludes Saturdays and Sundays but not public holidays, which vary by country.
Example calculation
From 1 March to 25 July of the same year (end date excluded):
March has 30 remaining days + April 30 + May 31 + June 30 + 25 July days = 146 days — about 20.9 weeks, with 104 of them weekdays.
Counting days between dates — the details
The subtle part of date math is whether the end date counts. The difference between Monday and Friday is 4 days — but a hotel stay from Monday to Friday is 4 nights, while an event running Monday through Friday spans 5 days. Deadlines, rentals, medications and legal notice periods each follow their own convention, so this calculator lets you choose.
Month-based breakdowns are also inherently fuzzy — months vary from 28 to 31 days — which is why the calculator shows both the exact day count and the calendar breakdown, and why contracts usually specify days rather than months.
Why use this calculator?
- Get exact day counts for deadlines, visas, notice periods and project plans — no off-by-one errors.
- See weekdays separately, the number that matters for business timelines.
- Handles leap years and month lengths perfectly, where manual counting fails.
Frequently asked questions
How many days are between two dates?
Subtract the earlier date from the later one. Computers do this by converting both to a day count and subtracting — exactly what this calculator does, so leap years and month lengths are automatically correct.
Should I include the end date in my count?
Depends on the context. Differences and ages exclude it; durations like event days, rental days and medication courses usually include it. If a deadline says "within 30 days", the safe reading is usually that day 1 is the day after the trigger date — but check the contract.
How do I count only working days?
The calculator shows weekdays (Monday–Friday) between your dates. For true business days you'd also subtract public holidays, which differ by country — a dedicated working days calculator is coming in a future update.
How many days until a specific date?
Set the start date to today and the end date to your target. The days figure is your countdown; the weeks figure helps for planning.