Find how many days, weeks and months are between two dates.
Enter a start and end date and this returns the elapsed time in years, months and days, plus totals in weeks, days and hours. It measures elapsed duration, so the gap from 1 March to 8 March is 7 days — the same answer your calendar app gives.
Most disputes about date arithmetic come down to whether both endpoints are counted. There are two defensible answers to "how many days from Monday to Friday":
Use the inclusive count (add one) for hotel nights versus days, days of annual leave, hire periods and event durations. Use the elapsed count for interest accrual, age, and most contractual deadlines. Getting this wrong by one day is the single most common error in date calculations, and it is worth stating explicitly whenever it appears in a document.
From 15 January 2026 to 6 August 2026:
Days and weeks are fixed units; months are not. The convention used here keeps the day number and advances the month, clamping to the last valid day where that date does not exist — so 31 January plus one month is 28 February in a common year.
This makes the operation non-reversible: adding a month to 31 January gives 28 February, but subtracting a month from 28 February gives 28 January. A breakdown like "6 months and 22 days" is therefore only precise in combination with the start date. For anything that must be exact — interest, legal deadlines, contractual terms — use the total day count.
Any period spanning 29 February picks up an extra day automatically. A year is a leap year if divisible by 4, except century years, which must also be divisible by 400. So 2024 and 2028 qualify, 1900 did not, and 2000 did. The rule exists because the Earth's orbital period is about 365.2422 days; the plain four-year rule overcorrects, and the 400-year exception brings the calendar back to within roughly one day in 3,200 years.
This counts every calendar day. For working days, a reasonable approximation is to multiply by 5/7 and then subtract public holidays — 203 calendar days is about 145 working days before holidays. The approximation drifts by up to two days depending on which weekday the period starts on, so count the actual weeks for a contractual deadline.
It is also worth checking which convention a document uses. "Within 30 days" almost always means calendar days; "within 30 business days" is more than six weeks. Some jurisdictions additionally define whether the day of the triggering event is day zero or day one, which shifts every subsequent date.
Interest calculations use formalised conventions that do not always match the actual number of days. Actual/365 and Actual/360 use real elapsed days over a fixed denominator, while 30/360 treats every month as 30 days and every year as 360. The last produces figures that differ measurably from a real day count — on a large principal, enough to matter. If you are checking a lender's interest figure against this tool, a mismatch is often a difference in convention rather than an error.
The calculation uses your device's local dates. For events in different time zones the result can be out by a day near midnight, since a deadline of "31 December" in one zone has already passed for someone several hours ahead. Where a single day matters, establish the deadline in the governing time zone first.
No — it measures elapsed days, so 1 March to 8 March is 7. Add one if you need both endpoints counted, as with days of leave or the duration of an event.
Months vary from 28 to 31 days, so they are not a fixed unit. The calculation advances the month while keeping the day number, clamping where necessary. Use the total day count when the figure has to be exact.
Yes, automatically. Any 29 February inside the period is counted. Leap years are those divisible by 4, except century years not divisible by 400.
Multiply the calendar days by 5/7 as a rough guide, then subtract public holidays. For a contractual deadline, count the actual weeks — the approximation can be out by up to two days depending on the starting weekday.
Probably a day-count convention. Financial calculations often use 30/360, treating every month as 30 days, or Actual/360, which divides real days by 360. Both give different results from a plain calendar-day count.