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Everyday math

Days Between Dates Calculator

Exact days between two dates, with the weeks/months/years breakdown and the business-days count, leap years handled.

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Quick answer

The count is calendar-exact, including leap days, 1 Jan to 31 Dec is 365 days in an ordinary year and in a leap year too (the year has 366, but the gap between its first and last day is 365). Business days exclude weekends.

Days
90
Breakdown
0y 2m 29d
Weeks
12
Business days (Mon–Fri)
65

Formulas last verified 2026-10-10. Results are estimates, not financial advice. How we calculate.

One subtraction, three conventions

Counting days sounds trivial and generates a surprising number of disputes, because three conventions coexist:

  • The gap (this calculator): start exclusive, end inclusive. Rent periods, ages, countdowns.
  • Both ends counted: gap + 1. Prescription days, event-day inclusive bookings.
  • Business days: the gap, weekends removed. Contract notice, court deadlines, delivery promises.

Most "the dates don't add up" arguments are two people using different rows of this list. The calculator shows the gap and the business-day count together so the difference is visible instead of argued.

Checks you can verify by hand

FromToDays
1 Jan 202431 Dec 2024365 (leap year, 366 days, 365 gaps)
28 Feb 20241 Mar 20242 (the leap day sits between)
28 Feb 20231 Mar 20231
Any MondayNext Monday7 · 5 business

Deadline arithmetic without surprises

  • Establish the convention first. "Within 30 days" of a contract may mean calendar or business days, and inclusive or exclusive of the trigger date, the document (or the statute) defines it, not intuition.
  • Watch the weekend landing. A 90-day calendar deadline landing on a Sunday usually rolls, forward for filings, sometimes backward for payments. The business-day count flags the risk.
  • Time zones can move the date itself. A UTC deadline is the evening before in US time zones and the morning after in India. Convert first, count second.

Related tools

To land on a date rather than measure one, "what is 60 days from signing?", use days from today. For a person's exact age in the same years-months-days form, the age calculator applies this arithmetic to birthdays, including the 29 February case. Weekly work hours across shifts are a different kind of time counting, the time card calculator handles those.

Frequently asked questions

Does the count include both dates?

It counts the gap, exclusive of the start date, inclusive of the end. Monday to Friday of one week is 4 days. If your context needs both endpoints counted (hotel nights vs stay days, medication doses), add 1 to the result; knowing which convention a form expects is half the battle.

How are leap years handled?

Exactly, the count walks the real calendar, so every 29 February in the span is included. That is why 1 Jan to 31 Dec is 365 days in a leap year too: the year holds 366 days, but the gap between its first and last day is one day less.

What counts as a business day?

Monday to Friday, excluding weekends. Public holidays are not excluded, they vary by country, state and even city, so a universal calculator would be silently wrong somewhere. For deadline-critical counts, subtract the holidays on your local calendar from the business-day figure.

Why does the months breakdown look odd for month-end dates?

Because months have different lengths, "1 month" from 31 January lands on 28/29 February under the clamped convention this calculator shares with timeanddate.com. The days total is always exact; the years-months-days breakdown is a human-readable approximation layered on top of it.

Can I count backwards?

Yes, swap the dates or just enter them in either order; the count shows as negative when "to" precedes "from", which itself is useful for "how overdue is this" questions.

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