Days Between Two Dates Calculator
Wondering how many days between two dates? This free days-between-dates calculator gives you the exact day count instantly — plus a full-weeks breakdown, approximate months and years, and the weekday name for each date. Perfect for trip countdowns, project deadlines, and anniversaries. Your dates never leave your browser.
Enter your dates
Your results
| Breakdown | Value |
|---|---|
| Full weeks | — |
| Months (approx.) | — |
| Years (approx.) | — |
Months and years are approximate averages — see "How it works" below.
How to use this calculator
Pick a start date and an end date with the date pickers — the calculator opens with today and 90 days from now. Results update automatically the moment you change either date, and you can press Calculate at any time to re-run the count.
By default the end date is not counted: January 1 to January 2 is 1 day. Switch to Include end date when you want both endpoints counted — for example, a trip or event running Monday through Friday.
The Swap dates button reverses your two dates without retyping, which is handy when you're counting backward from a deadline.
How it works
Every date you enter is converted to a UTC midnight timestamp with Date.UTC(year, month, day) — the same instant in time regardless of your device's time zone. The difference in milliseconds is divided by 86,400,000 (the number of milliseconds in a day) and rounded. Because the math happens in UTC, a daylight saving time change can never add or remove a day from your count.
The day count is the number of 24-hour boundaries crossed between the two dates. With the end date excluded, January 1 to January 2 is 1 day; the "Include end date" toggle adds 1 so that both the first and last day count. Full weeks are the day count divided by 7, rounded down, with the leftover days shown alongside.
Months and years are labeled approximate because calendar months (28–31 days) and years (365 or 366 days) are not a fixed length. Months use the average Gregorian month — 365.25 ÷ 12 = 30.4375 days — and years use the average year of 365.25 days. Weekday names are read from the UTC date, so they are exact.
Frequently asked questions
Does the count include the end date?
By default, no. The end date is excluded, so January 1 to January 2 counts as 1 day. If you want both the first and last day counted - for example, a vacation running Monday through Friday - turn on the 'Include end date' toggle and the same pair counts as 2 days.
How are months calculated?
Months are an approximate value: the total days divided by 30.4375, the average month length in the Gregorian calendar (365.25 days divided by 12). Because real months are 28 to 31 days long, this figure is labeled 'approx' and should not be read as whole calendar months.
Why might other calculators differ by one day?
The usual reason is whether the end date is included: some tools count both endpoints, some do not. Differences can also come from time zones and daylight saving time when a calculator works in local time instead of UTC. This calculator converts every date to UTC midnight first, so a DST shift can never add or remove a day.
Can I count business days?
This calculator counts calendar days, including weekends and holidays. Business-day counting follows different rules - weekends plus public holidays, which vary by country and year - so it is not part of this tool.
Does the calculator handle leap years?
Yes. Every day is counted exactly once based on UTC timestamps, so leap day February 29 is included automatically. A span that crosses a leap day simply counts one day more than the same span in a common year.