Days Between Dates

There are two defensible answers to the same question, and they differ by one. Counting the nights between the dates gives you the difference: 1 March to 5 March is four. Counting the days you are actually present for, including both ends, gives five. Neither answer is wrong — which one you want depends on why you are asking. A hotel bill counts nights; a leave request usually counts both the first day and the last.

That is exactly what the include the end date control is for. It is visible rather than assumed, so the number on screen is one you can defend when someone checks it. The start date and end date can be entered in either order — if the end lands earlier than the start, the calculator swaps them and says so instead of just handing you a negative number.

Weeks are simple: the span in days divided by seven, shown as whole weeks with the leftover days named on their own instead of folded into a decimal. Months are not simple, because a month runs anywhere from 28 to 31 days and the answer depends on exactly which months your span crosses.

The calculator gives months as calendar months, not as days divided by thirty. It steps forward from the start date one whole month at a time for as long as the result is still on or before the end date, then reports whatever days are left. Stepping from 31 January lands on the last day of February, since there is no 31 February, and the same clamping applies wherever a short month gets crossed. A figure produced by dividing by thirty will disagree with a real calendar for most spans, which is exactly why payroll cutoffs, notice periods and contract terms are all written in calendar months.

The business days figure counts Monday to Friday inside the span, and the weekend figure counts the Saturdays and Sundays, so the two add up to the plain day count. That split answers the question people usually mean — how many working days are left before a deadline — without needing a separate tool for it.

What it does not do is remove public holidays. Holidays differ by country, by region and sometimes by company, and a number that quietly assumed one calendar would be wrong for most of the people reading it. This calculator would rather be exact about what it counted than guess about what it assumed, so subtract the holidays that apply to you from the business day figure yourself. It also does not assume a working week that runs Monday to Friday for everyone, since that is not universal either. Everything here is computed in your browser from plain calendar dates, with no time zone involved and nothing sent anywhere. To land on a date instead of measuring the gap between two you already have, the date calculator adds or subtracts a span from a date you give it.

When the second date is simply today, choose Days since a date. There is one field, filled with today's date so you only have to move it back, and the count runs to today in your own calendar: days, then weeks and days, then calendar months and days, and years, months and days once the span passes a year. The date it counted to is written under the field, so a screenshot taken tomorrow still says which today it meant.

The same off-by-one choice applies. By default the day itself is day zero, which is the elapsed-time answer; tick count today as a day if you number days from day one, the way a streak or a sobriety counter does. A date after today gives the days until it and says so. Copy link puts the date in the address as ?since= followed by the date, and whoever opens it gets the count to their own today, which is what a days-since link is for. It's the same calendar arithmetic as the two-date mode, so a span across the night the clocks change counts that night as one day.