Two dates. Nights and days sorted.

Hotel nights = check-out (or departure) date minus check-in (or arrival) date in whole days. Inclusive calendar days = nights + 1, counting both ends. Arriving 10 March and leaving 16 March is 6 nights and 7 calendar days.

Hotels bill the nights you occupy a room. Leave forms and many flight searches count calendar days. Put both dates in the calculator when a booking, a leave request and a ticket disagree.

A listing that says 3 nights means three sleeps between check-in and check-out. Friday check-in and Monday check-out is Friday, Saturday and Sunday night — 3 nights — and four calendar days (Friday through Monday).

Same-day arrival and departure is 0 nights and 1 calendar day. A 10-night stay is 11 calendar days. The tool uses that convention; it does not add extra nights for a late check-out unless you change the dates.

If a hotel or package shows “3 nights”, plan 4 calendar days of leave if you need the check-out morning at home or at work. Checking in Friday after work and checking out Monday still uses Monday as a calendar day even when you fly that afternoon.

“3 days, 2 nights” on a tour is the other way around: 2 hotel nights across 3 calendar days. Read which unit the vendor used before you match it to a leave form.

Leave often starts the calendar day you fly out and ends the calendar day you land. Hotel nights start at check-in. A Friday night flight plus a Saturday check-in is 0 hotel nights on Friday and still 1 leave day. Enter the hotel dates and the travel dates separately if they differ.

On a multi-city trip, do not add each stay’s calendar days and expect the trip total. Shared check-out/check-in days would be counted twice. Use one date pair for the whole trip, or add nights stay by stay and calendar days only once for the outer dates.

Use it to match a hotel voucher to a leave request, to confirm a host’s check-out date, and to see how many days a “nights” package actually spans.

Use it before buying connecting hotels so you do not pay for an unused night or leave a gap. Do not use it for visa, Schengen or other legal stay limits — those have their own inclusive-day rules.

The usual error is treating nights as days: Friday to Monday is 3 nights, not 4. Another is counting same-day in-and-out as more than 0 nights.

A third is lining up the flight ticket’s calendar with the hotel without noticing a night in the air. If you leave Thursday evening and check in Friday, Thursday is a leave day and not a hotel night.

The tool uses the hotel-and-travel convention: nights between two calendar dates, inclusive days = nights + 1. Date maths follows the calendar, including month ends and leap days. It is not legal advice.

Visa and residence clocks may count entry and exit differently. Use official calculators for those. This page only separates a booking’s nights from a leave form’s days.