calc / date & time / DAYS
Day Counter
Days between any two dates, with the fencepost question answered explicitly — plus business days, weekends, and the span as weeks, months and a share of the year.
Count the days between two dates
§1How day counting works
Every day-counting argument is the same argument: do you count the posts or the gaps between them? The fencepost problem. There are exactly two honest answers, and this page shows the one you pick with the checkbox:
Neither is wrong. A hotel bills you exclusive (nights). A leave application is read inclusive (Monday to Friday off is five days of leave). The mistakes happen when two parties silently assume different conventions.
1 January 2026 to 31 March 2026. 31 March is day 90 of the year (31 + 28 + 31) and 1 January is day 1, so exclusive = 90 − 1 = 89 days and inclusive = 90 days. As weeks that's 12 weeks and 5 days exclusive; in approximate months, 89 ÷ 30.44 ≈ 2.92 months; as a share of the year, 89 ÷ 365.25 ≈ 24.4%.
§2The gotchas
Banks and courts almost always count exclusive of one end — interest for "1st to 10th" is 9 days, not 10. Rent, notice periods and penalty clauses each have their own habit. If money rides on the count, check which convention the document uses before you argue about one day.
The business-day figure here counts weekdays only. Public holidays in India vary by state — Maharashtra, Tamil Nadu and Kerala can disagree on the same week — and banks add second/fourth Saturdays off. Subtract your local holiday list yourself.
The "% of a year" figure divides by 365.25, the long-run average. In a real leap year the same span is a slightly smaller share, and in a common year slightly larger — fine for intuition, not for pro-rata contracts, which should name a day-count basis.
§3Related
Date calculator to add or subtract days from a date, time duration calculator for gaps measured in hours and minutes.