~/days-between-dates-free-calculator apps ← back to terminal

🌐 Language

// free tool
██████╗ █████╗ ████████╗███████╗███████╗ ██╔══██╗██╔══██╗╚══██╔══╝██╔════╝██╔════╝ ██║ ██║███████║ ██║ █████╗ ███████╗ ██║ ██║██╔══██║ ██║ ██╔══╝ ╚════██║ ██████╔╝██║ ██║ ██║ ███████╗███████║ ╚═════╝ ╚═╝ ╚═╝ ╚═╝ ╚══════╝╚══════╝

Days Between Dates Calculator_

Count exact days, business days, weeks, months between any two dates. Live countdown timer, date arithmetic, Unix timestamps & format converter — 100% free, no signup.

—
days
// timeline
weekday distribution
weekdays vs weekends
// quick countdowns & anniversaries
// age & birthday calculator
// date arithmetic — add or subtract from a date
±
—
// live countdown timer
COUNTING DOWN
00
days
:
00
hours
:
00
min
:
00
sec
// date format converter

Counting days, business days and deadlines — the full answer

Everything below is answered in full: whether to include the end date, how business days and public holidays really work, how ages and leap days behave, what a Unix timestamp is, why two calculators can disagree by exactly one day, and how to write a date that nobody can misread.

01. Using the calculator

What can this tool do?

Five things: count the exact time between two dates, work out an age on any reference date, do date arithmetic (add or subtract days, weeks, months or years), run a live countdown to a target date, and convert a date between formats including Unix timestamps and ISO 8601.

Is it free? Do I need an account?

Completely free, no account, no ads and no limit on how many calculations you run.

Can I share a result with someone?

Yes — Share link puts the dates in the URL, so whoever opens it lands on the same calculation. Nothing is stored on a server; the link carries everything it needs.

Does it work offline and on a phone?

Both. Once the page has loaded, every calculation runs locally, so it keeps working with no connection, and the layout adapts to a phone screen.

Is my data private?

Yes. Dates are calculated in your browser and never transmitted — which matters more than it sounds when the dates are a contract deadline, a medical appointment or an employment notice period.

Is it available in other languages?

The interface is available in ten: English, Dutch, Spanish, French, German, Portuguese, Russian, Japanese, Arabic and Indonesian. The maths does not change — only the labels do.

02. Counting days correctly

Should I include the end date or not?

It depends on what you are counting, and this is where most disputes start. Counting nights in a hotel or days of interest? Exclude the end date — 3 to 5 March is two nights. Counting days of a festival or days worked? Include it — 3 to 5 March is three days. The Include end date toggle switches between the two, so decide which question you are asking before you read the answer.

Why does another calculator give me a different number?

Nine times out of ten it is the inclusive/exclusive difference above, and the two answers differ by exactly one. The rest is usually time zones: if one tool works in UTC and you are in a zone ahead of or behind it, a date can land on either side of midnight.

What does the weeks and months breakdown mean?

Days are exact; weeks are just days divided by seven. Months and years are approximations, because months are not the same length — the breakdown gives you calendar months where whole months fit, and the remainder in days. For anything contractual, quote the day count, which is unambiguous.

How many days are in a month, for calculation purposes?

There is no single answer, which is precisely the problem. “One month” from 31 January is 28 February in most conventions (there is no 31 February), while “30 days” from 31 January is 2 March. If a contract says one month and the deadline matters, check which convention the contract itself uses — the calendar cannot decide it for you.

Does it count partial days?

The day count is whole days between the dates; the breakdown also shows the total in hours and minutes, which is where partial days appear. If you need to bill or charge in fractions of a day, work from the hours figure rather than rounding the day count.

How do I count backwards from a deadline?

Use the date arithmetic tab: set the deadline as the base date, choose the amount, and set the direction to subtract. “Fourteen days before completion” is one calculation rather than a finger-count across a wall calendar.

Why is the answer one day less than I expected?

Because the default convention excludes the end date: it measures the gap between two dates, not how many dates are covered by the range. Turn on Include end date and the number matches what you counted on the calendar.

03. Business days and working time

How do I count business days?

Switch on the Business days (Mon–Fri) option and Saturdays and Sundays are removed from the count. This is the figure most contracts, SLAs and notice periods mean when they say “working days”.

Are public holidays excluded?

No — you must subtract those yourself. Holidays differ by country, by region and sometimes by industry: a calculator cannot know whether your Monday is a bank holiday in Belgium, a public holiday in Ontario or an ordinary working day. Count the business days here, then deduct the holidays that fall inside the range.

What counts as a working day in a contract?

It varies by jurisdiction and by the wording of the contract itself. Many define it explicitly — “any day other than a Saturday, Sunday or public holiday on which banks are open in London” is a common formulation. If the contract defines it, that definition wins over any calculator.

How do I work out a “within 5 business days” deadline?

Set the trigger date, add five, and count only weekdays — then check whether any public holidays fall in that window and push the deadline out by that many days. Also check whether the clock starts on the trigger day itself or the next day; “within 5 business days of receipt” usually means the count starts the following working day.

Do banking days differ from business days?

Sometimes. Payment systems have their own calendars — a SEPA or Fedwire cut-off can make a Friday afternoon transfer a Monday transaction, and some financial contracts specify banking days in a named city. If money is moving, the relevant calendar is the payment system's, not the office's.

What about a four-day week or shift work?

The Mon–Fri filter assumes a conventional week. For a compressed or rotating schedule, count the total days here and apply your own ratio, or count the calendar weeks and multiply by the shifts per week — the calculator gives you the raw range to work from.

04. Age, anniversaries and countdowns

How is age calculated?

In completed years, then the leftover months and days — the way people actually state an age. Someone born on 3 March 1990 turns 36 on 3 March 2026 and is 35 the day before, regardless of how many days have elapsed.

Can I work out an age on a past or future date?

Yes — set the reference date to whatever you need. That is the useful case for eligibility questions: how old someone will be on the first day of term, at the date of an event, or on a policy renewal date.

What happens with a 29 February birthday?

In non-leap years the anniversary falls on either 28 February or 1 March depending on the convention in play, and different jurisdictions genuinely differ on which. This calculator counts completed years, so a leapling born 29 February 2000 completes 26 years during 2026 — but if a legal age threshold hangs on it, check the rule that applies where you are.

How do I count down to a date?

Use the countdown tab: set a target date, give it a label, and it ticks live. Useful for a launch, a deadline, an exam, a wedding or a flight — and the share link means everyone is looking at the same clock.

How many days until my next birthday or anniversary?

Set the target to this year's date; if it has already passed, use next year's. The countdown then handles the rest, including the leap day if one falls inside the range.

Can I use this for a legal or medical deadline?

It will give you the arithmetic accurately, but arithmetic is not the whole answer. Limitation periods, notice periods and appeal windows have their own rules about when the clock starts, whether weekends count and what happens when a deadline lands on a holiday. Use the number here as your working figure and have anything consequential confirmed by the person responsible for it.

05. Calendars, leap years and edge cases

What is the leap year rule, exactly?

A year is a leap year if it divides by 4 — except century years, which must divide by 400. So 1996 and 2024 are leap years, 2000 was, 1900 was not and 2100 will not be. That last one catches a surprising amount of software.

Does the calculator handle leap days?

Yes. A range that spans 29 February includes it, which is why a year-long range can come out as 366 days rather than 365 — that is correct, not a rounding error.

What about daylight saving time?

In regions that observe it, two days a year are not 24 hours long: one is 23 hours and one is 25. Day counts are unaffected because a calendar day is still a calendar day, but an hours-and-minutes total across such a change will be an hour short or long compared with a naive 24-hour multiplication.

Do time zones affect the result?

They can, at the edges. A date is not a moment — “3 March” starts and ends at different instants around the world. If you are comparing against a system that stores instants in UTC, a late-evening local date can be the following day in UTC, which is the classic source of an off-by-one between two tools.

What are ISO week numbers?

The international convention for numbering weeks: weeks start on Monday, and week 1 is the week containing the first Thursday of the year (equivalently, the week containing 4 January). It matters because the US convention starts weeks on Sunday and numbers them differently — “week 32” means two different things depending on who wrote it.

Why do very old dates behave strangely?

Because the calendar itself changed. The Gregorian reform skipped days to correct accumulated drift: Catholic countries jumped from 4 October straight to 15 October 1582, while Britain and its colonies did not switch until 1752, when 2 September was followed by 14 September. Software calculates the modern calendar backwards through those gaps, which is arithmetically consistent but historically inaccurate for dates before the local switch.

Does it handle dates before 1970 or far into the future?

Yes for ordinary date arithmetic — birthdates in the 1930s and deadlines in 2099 are fine. Unix timestamps are the exception worth knowing about: they are counted from 1970, so earlier dates produce negative values, which some systems reject.

06. Timestamps, formats and other software

What is a Unix timestamp?

The number of seconds since 1 January 1970 00:00:00 UTC. Because it is a single number in a fixed zone it is unambiguous, which is why APIs, logs and databases use it in preference to anything human-readable.

Seconds or milliseconds?

Both are in circulation and mixing them up is a classic bug. A ten-digit number is seconds; thirteen digits is milliseconds — JavaScript's Date.now() returns milliseconds, most Unix tooling uses seconds. If a date comes out in 1970 or in the year 55000, that is what happened.

What is the year 2038 problem?

Systems that store Unix time in a signed 32-bit integer overflow on 19 January 2038 at 03:14:07 UTC and wrap to 1901. Modern platforms use 64-bit values and are unaffected, but embedded devices and old file formats are still out there — it is the same class of problem as Y2K, with a harder deadline.

What is ISO 8601 and why should I use it?

The international standard format: 2026-08-18, year-month-day, largest unit first. It sorts correctly as plain text, it cannot be misread, and it is what to use in filenames, spreadsheets and anything crossing a border.

Is 03/04/2026 the third of April or the fourth of March?

Both, depending on the reader — day-first in most of the world, month-first in the United States. This ambiguity causes real damage in contracts, shipping and medical records. Writing 2026-04-03, or spelling the month out, removes it entirely.

How do dates work in Excel and Google Sheets?

As serial numbers: day 1 is 1 January 1900 and every date is a count from there, which is why subtracting one date cell from another gives you a plain number of days. Excel also preserves a famous bug — it treats 1900 as a leap year for compatibility with an even older product — so serial numbers before 1 March 1900 are one off.

Which spreadsheet formulas do the same job?

=B1-A1 gives days between two dates. =NETWORKDAYS(A1,B1,holidays) gives working days and, unlike this calculator, will take a holiday list. =DATEDIF(A1,B1,"m") gives whole months, and =EDATE(A1,3) adds three months. Use this page for the quick answer, a spreadsheet when the same calculation has to run over hundreds of rows.

What other formats does the converter produce?

The same instant expressed as ISO 8601, a Unix timestamp, an RFC-style string of the kind email headers and HTTP use, and readable long-form dates — which is what you need when a system rejects your input and you are not sure which shape it wants.

07. Troubleshooting

The result looks off by one day.

Check the Include end date toggle first — that accounts for almost every off-by-one. If it persists, check whether the other source is working in UTC while you are in a different zone, and whether one of you started counting on the trigger day and the other on the day after.

My business-day count does not match my employer's.

Almost certainly public holidays, which are not deducted automatically here, or a company calendar with shutdown days. Compare the two counts: the difference is usually exactly the number of holidays in the range.

A date I typed was rejected or interpreted oddly.

Use the ISO form YYYY-MM-DD, or the date picker, and the ambiguity disappears. Typed dates are interpreted by the browser's locale, so 03/04/2026 can be read either way depending on the machine's settings.

Can I print or save a calculation?

Use your browser's print or save-as-PDF for a paper record, and the share link for a reproducible one — the link reopens the exact calculation rather than a picture of it.

Which browsers does it work in?

Any current browser on any operating system. There is nothing to install, no plugin and no server — if the page loads, the calculations work.