Time between dates
Two dates in, and the length of that date range comes back as a calendar breakdown plus the total in every unit. Ten years is 3,653 days, 87,672 hours or 5.26 million minutes. The same panel counts down to a date still ahead, and counts months as whole calendar months rather than 30-day blocks.
How to measure time between dates
The hour and minute figures here assume midnight to midnight, since only dates are entered. That makes them exact multiples of 24 and 1,440, which is useful for a sense of scale and useless if what you need is the gap between two specific moments. Anything crossing a daylight saving boundary gains or loses an hour in local time, which is precisely why the calculation is done in UTC.
The months figure is the one that produces arguments. A calendar month runs from a date to the same date in the next month, so 15 January to 15 March is exactly two months whatever February happens to be, while a month-end start clamps instead: 31 January to 1 March comes out as one month and one day, not two days. That span is 29 calendar days in a common year, so dividing by an average month of 30.44 days gives 0.95 months — under one where the calendar count says just over one, which is the disagreement in miniature. Neither method is wrong; they answer different questions, and the calendar one is what a tenancy or a contract term means.
Finance uses a third method again, and it is worth knowing about because it explains a whole class of small discrepancies. Many bonds, loans and swaps accrue interest on a 30/360 day count, which declares every month thirty days long and every year 360, so a coupon period is always the same size and the arithmetic needs no calendar at all. It is a deliberate fiction with a name, and it is the usual reason an interest figure sits a day or two away from what this panel reports.
The last decision the panel asks you to make is whether both end days count. A holiday from Monday to Friday is five days because you occupy both ends; a countdown from Monday to Friday is four because you are measuring a gap. The same ambiguity sits under the bare word "days": thirty working days is 42 calendar days, six weeks exactly, which is why a document that means one of them should say so.
What people use it for
- Getting a sense of scale for a long span
- Counting down to a launch or an event
- Checking a contractual deadline in calendar days
- Working out length of service
- Measuring a booking or leave period
- Stating the length of a date range in a report
- Using it as a week, month or year counter
- Working out nights against days for a hotel stay
- Reporting a project length in every unit
- Choosing how to phrase a duration
- Counting a subscription term in months
- Counting months of service or tenancy
- Tracking a pregnancy in weeks
- Checking an anniversary
Questions
Enter both. The elapsed span reads as a breakdown in years, months and days, with the total in every other unit underneath it.
Switch to the countdown tab. Today is filled in for you and the gap is counted in whole days.
All three come back at once. Weeks are the days over seven, so ninety days is 12.857 weeks, or twelve whole weeks and six days. Months run from a date to the matching date in a later month, so 15 January to 15 March is two. Years are complete anniversaries, and the last one only counts once its anniversary has passed.
It clamps to the end of a shorter month. 31 January plus one month is 28 or 29 February, so 31 January to 1 March is one month and one day. That is the whole method: whole months are added to the earlier date until one more would overshoot, and whatever is left over is counted in days.
Usually, for a period you occupy: leave, a hire, a tenancy. A range from 1 to 31 January is 31 days counted inclusively and 30 as a gap, so Monday to Friday off is five days of leave rather than four. For a gap between two events, take the exclusive count instead. The switch adds or removes exactly one day.
Four. A hotel is the one common case where the exclusive count is the right one, because the last date is a checkout rather than a day you occupy.
Because a month is not a fixed length. Counting calendar months gives one answer and dividing the days by 30.44 gives another. Neither is wrong.
Divide the day count by 365.2425 for a year, the average length across the Gregorian cycle, or by 30.44 for a month. The years and months rows here are whole ones on purpose — they count completed anniversaries, so the figure only moves on the anniversary itself and a decimal would be a different quantity rather than a more precise version of the same one. Take the decimal for an average or a rate, and the whole count for anything a contract has to agree with.
Any day at all, including weekends and public holidays. "Within 30 days" means calendar days unless a document says otherwise.
Thirty working days is 42 calendar days; six weeks exactly. Working days and business days are the same thing under two names, and the gap against calendar days is the whole reason the distinction is worth writing down.
A count that excludes both the first day and the last, which is how notice periods in court rules and company law are often written. Three clear days from a Monday runs Tuesday to Thursday and expires on the Friday, so it is a day longer than it sounds.
Because no time of day is entered, so the span is measured midnight to midnight. Hours come out as days times 24 and minutes as days times 1,440, always exactly. For the gap between two specific moments you want a duration calculator, not a date one.
No. Everything is calculated in UTC, so a clock change cannot add or remove an hour from the count.
Dividing the days by seven gives 52.14 in a common year and 52.29 in a leap one, never exactly 52, which is why a weekly cycle drifts against the calendar. Counting numbered ISO weeks is a different question with a different answer, and the week number tool has it.
Because it counts completed weeks plus days from the date of the last period, which is a convention rather than a plain division. Here, ninety days is 12.857 weeks; an app would call the same span 12 weeks and 6 days.
The largest one that still conveys precision. "Nine hundred days" and "two years five months" are the same span and land very differently.
A past date turns the countdown into a count up. Order never changes the size of the span, only which date the breakdown reads towards.