Date Calculator
Two tools in one: count the time between two dates (including business days), or add/subtract days from a date to find a deadline.
1. Days between two dates
2. Add or subtract days
Inclusive or exclusive counting?
This calculator counts the days between dates — Monday to Friday of the same week is 4 days. Some situations (rental periods, medication courses, ticket validity) count inclusively, where Monday to Friday is 5 days: just add 1 to the result. Legal deadlines usually exclude the starting day and include the deadline day, but always check the specific rule.
Business days
The result also shows weekdays only (Monday–Friday), which is what most contract and shipping deadlines mean by "business days." Public holidays vary by country and aren't subtracted — knock off any that fall in your range.
Handy rules of thumb
- A year is 365 days (366 in leap years — years divisible by 4, except century years not divisible by 400).
- 30 days ≈ 4 weeks and 2 days; 90 days ≈ just under 3 months.
- To find "the same day next month" mentally, add 28, 30, or 31 depending on the month — or just use tool 2.
- 52 weeks is 364 days, which is why your birthday shifts one weekday per year (two after a leap day).
Frequently asked questions
Does the calculator handle leap years?
Yes — it uses the real calendar, so February 29, month lengths, and century rules are all handled exactly.
What does "90 days from today" mean for a deadline?
Usually the 90th day counting the day after today as day 1. Enter today in tool 2 and add 90; if your contract counts today as day 1, add 89 instead.
How do I count months between dates?
The result shows a years/months/days breakdown alongside total days. Months vary in length, so "3 months" is defined calendar-to-calendar (Jan 15 → Apr 15).