Date Difference Calculator
Pick two dates and read the gap between them four different ways. Tick the weekdays that count as working days and you get a business-day figure alongside the raw one, which is usually the number you were actually after.
Why two date calculators give different answers
Ask how many days there are between 1 March and 3 March and you can defend two answers. Two, if you are counting the gaps between the dates. Three, if you are counting the dates themselves. This is the fencepost problem, and it is the single biggest source of disagreement between date tools.
Both answers are used in real life. A hotel charges you for two nights. A conference that runs 1 to 3 March lasts three days. A contract that gives you "14 days to respond" almost always means the deadline is 14 days after the letter, not 13. The Count the end date itself switch above picks your convention: off gives the gap, on gives the number of dates in the range. It moves every figure on the page, not just the total, so the breakdown and the day count never disagree.
Months are not a fixed length, so the breakdown is a convention
The years-months-days figure cannot be derived from the total. There is no fixed number of days in a month, so the answer depends on which month you borrow from when the day numbers do not divide cleanly.
This tool adds whole months first and clamps to the end of the month when the day number does not exist, then counts the leftover days from there. One month after 31 January is 28 February, so 31 January to 1 March comes out as 1 month and 1 day. Calculators that instead subtract the day numbers and borrow from whichever month is handy land a day or two away from that on the same pair. Neither is wrong, and that is the problem. If a precise duration matters, quote the total day count — it has exactly one correct value.
The same trap sits behind "how many months is my loan". Multiply months by 30 and you will be several days out per year, every year.
What the working-days figure knows
It knows which weekdays you ticked, and nothing else. That is deliberate — a working week is Monday to Friday in most of the world, Sunday to Thursday in much of the Middle East, and Monday to Saturday in plenty of trades. Tick what applies and the count follows.
What it does not know is your public holidays. There is no holiday calendar here, because holidays depend on a country, often a region within it, and sometimes on which sector you work in. If you need a legal deadline in business days, count the weekdays here and subtract the holidays by hand from the official list. A calculator that guesses your country's holidays and gets a regional one wrong is worse than one that admits it does not know.
Daylight saving, and why this works in whole days
Subtracting two local timestamps and dividing by 86,400,000 is the obvious approach and it is subtly broken. Wherever clocks change, one day of the year is 23 hours long and another is 25. A span that crosses a spring-forward date comes out at 29.958 days instead of 30, and rounding rescues you right up until the day it does not.
Every date here is handled at UTC midnight, where no clock change exists, so a calendar day is always one day. The consequence is the total-hours line: it is calendar days multiplied by 24, which is the number you want for planning and not the number a stopwatch would record across a clock change.
Dates before 1582
The calculator uses the proleptic Gregorian calendar — today's rules, extended backwards forever. Real history did not work that way. Britain and its colonies switched from the Julian calendar in September 1752 and deleted eleven days to do it, so 2 September was followed by 14 September. Russia switched in 1918 and deleted thirteen.
For any date in the last few centuries in most of the world this makes no difference. For genealogy, old legal records or anything before the switch in that country, the number you get here will not match the number of days people actually lived through.
Frequently asked questions
How many days are there between two dates — is the end date included?
That is your choice, and it changes the answer by one. By default the tool counts the gap between the dates, so 1 to 3 March is two days. Tick "count the end date itself" and it counts the dates in the range instead, giving three.
How do I count business days between two dates?
Tick the weekdays that count as working days and read the working-days line. It handles any pattern, including a Sunday to Thursday week. Public holidays are not included — subtract those yourself from your national list.
Why is one month sometimes 28 days and sometimes 31?
Because months genuinely differ in length, so the years-months-days breakdown depends on which month gets borrowed from. This tool borrows from the month before the end date. If you need a figure nobody can argue with, quote the total number of days.
Does it handle leap years?
Yes. Every span is measured against the real calendar, including 29 February and the century rule that skips leap years in 1900 and 2100 but keeps 2000. No approximation of 365.25 days is used anywhere.
Can I work out the number of weeks between two dates?
Both forms are shown: a whole number of weeks with the leftover days, and a decimal total for when you need to multiply something by it. The decimal is rounded to two places.
Last updated September 19, 2026