About

DateSum is a set of fast, free date calculators: days from today, business days, days between dates, age, and live holiday countdowns. It exists because date arithmetic fails people at the worst moments — missed return windows, visa overstays, late filings — and most answers online are either ad-walled or subtly wrong about conventions.

Every calculation here uses the conventions of courts and banks: today is day zero, calendar counts include weekends, business-day counts skip them, and all arithmetic is done on whole calendar days anchored to noon UTC, so daylight-saving transitions can never shift a result. Movable holidays are computed from their actual rules (Easter from the ecclesiastical algorithm, Thanksgiving as the fourth Thursday of November), not from lookup lists that go stale.

The site is intentionally lightweight: no accounts, no tracking beyond basic analytics/advertising described in the privacy policy, and every tool runs instantly in your browser.

Questions or corrections? Get in touch — accuracy reports are especially welcome.