What is the difference between days and inclusive days?

Days counts midnights between dates (Mon→Tue = 1). Inclusive counts both endpoints (Mon→Tue inclusive = 2). Use days for durations, inclusive for bookings and leave.

How are weekdays counted?

Each day in [start, end) is tested; Mon–Fri count as weekdays, Sat–Sun as weekends. Public holidays are not auto-removed — subtract them manually.

Does it handle leap years?

Yes — real calendar subtraction includes 29 Feb automatically. No 365-day approximation.

Can I count backwards?

Yes. Enter dates in either order; the span is absolute. For direction (overdue vs remaining), note which date is earlier.

How do I prorate rent by days?

Monthly rent × days ÷ 30.4375 (average month), or annual rent ÷ 365.25 × days for precision. Landlords usually specify the method — ask.

Time & Date · Free tool

Date Difference Calculator

Days between dates — with weekdays, weekends and inclusive counts.

How many days between 3 March and 27 June? How many working days in a notice period? How long until a visa expires? Counting on fingers or in spreadsheets invites off-by-one errors — the most common date bug in contracts, payroll and project plans. This date-difference calculator returns the exact day count between any two dates, plus weeks, approximate months/years, a weekday-vs-weekend split, inclusive counts, and total hours and minutes.

The tool counts the half-open interval [start, end) by default — the standard for durations — and also shows the inclusive count (both endpoints) used for bookings and leave ('Monday to Friday inclusive is 5 days'). Weekday analysis walks each day so bank-holiday-style exclusions start from truth, and leap years are automatic because real calendar arithmetic is used, not 365-day shortcuts.

Enter start and end in either order; the calculator sorts them and reports the absolute span. Ideal for HR notice periods, tenancy lengths, pregnancy due-date spans, project timelines, and countdowns.

Updated 2026-09-01 · 6-min read · Formula + steps included

● Date Diff workstation

Time & Date →

Date-difference method

days = round((end − start) ÷ 86,400,000); weekdays = count of Mon–Fri in [start, end)

Dates are normalised to local midnight, subtracted in milliseconds, and divided by the milliseconds-per-day. Weekdays are counted by iterating each day and testing day-of-week — O(n) but exact, avoiding month-length tables entirely. Inclusive days = days + 1; months ≈ days ÷ 30.4375 (mean Gregorian month); years ≈ days ÷ 365.25.

start / end: Any two calendar dates. Order does not matter; span is absolute.
days: Nights/midnights between dates — e.g. Mon→Tue = 1 day.
inclusive: Days including both endpoints — Mon→Fri inclusive = 5.

Worked example: 1 Apr 2026 → 15 May 2026

A contractor's 6-week placement spans these dates:

Normalise both to midnight; subtract: 15 May − 1 Apr = 44 days.
Weeks: floor(44 ÷ 7) = 6 weeks + 2 days.
Walk each day: 32 weekdays, 12 weekend days.
Inclusive bookings count: 44 + 1 = 45 days.
Approx months: 44 ÷ 30.4375 ≈ 1.45 months; hours = 1,056.

Result: 44 days (6w 2d) — 32 weekdays, 12 weekends; 45 inclusive; ~1.45 months.

How to use this calculator

built for contracts where one day costs real money.

Step 1: Pick start date

Contract start, booking check-in, employment first day — any past or future date.

Step 2: Pick end date

End, deadline, or due date. Either order works; the span is absolute.

Step 3: Press Calculate

Read days, weeks, weekday split, inclusive count, and hour/minute totals.

Step 4: Choose the right count

Use 'days' for durations and interest; 'inclusive' for leave, hotel nights+1, and 'Monday-to-Friday' bids.

Use cases

Where exact day counts decide outcomes:

Notice periods & HR

A 4-week notice from 5 May ends 2 June (28 days). Weekday splits separate paid working days from weekends.

Tenancies & lets

Deposit protection, break clauses and prorated rent (£1,200 × 17 ÷ 30.44) all start from day counts.

Projects & sprints

44 days at 5-day weeks = ~32 delivery days. Subtract holidays for realistic velocity.

Travel & visas

'90 days in any 180' Schengen math and 45-day inclusive holiday lets hinge on the +1 rule — get it right here.

Health timelines

Pregnancy (280 days from LMP), medication courses (14 inclusive = 13 intervals + first dose), and isolation windows.

Pro tips

Avoid the classic off-by-one:

Say 'inclusive' or 'exclusive' in every contract line — never bare '5 days'.
For payroll, multiply weekdays by daily rate, not days × 5/7 — weekends distort short spans.
Subtract public holidays from weekdays for true working days (England averages 8/year).
For spans over a year, quote years+days ('1y 44d'), not just 409 days.
Screenshot the breakdown for disputes — method beats memory.