This online time and date calculator is available to everyone, completely free to use, and requires no sign-up. Below, you’ll find information about what it does, how it works, and answers to the specific questions people usually run into.
What This Calculator Does
This days between calculator comes with three modes, which you can switch between using the buttons at the top of the tool.
Date & Time finds the exact gap between two moments, down to the second, factoring in the clock time on both ends and an optional time zone for each side.
Dates Only finds the gap between two calendar dates when the time of day doesn't matter, with a toggle for whether to count the first and last day.
Add / Subtract goes the other direction: start from one date and add or subtract a number of days, weeks, months, or years to land on a new date.
All three give a full breakdown in years, months, and days, along with running totals. In Date & Time mode, the calculator also works as an hours, minutes, seconds calculator, showing the exact duration between two moments. It handles leap years, months of different lengths, and daylight-saving-time changes without you needing to work them out manually.
Who It's For
- Working out a deadline, renewal date, or notice period
- Finding someone's exact age, or the number of days since a milestone
- Building a timesheet or checking payable hours for a shift
- Coordinating a meeting or call across time zones
- Any quick "how many days until" or "how many hours between" question
How It Works
Behind the scenes, the calculator converts every date and time into a single, continuous number before doing the math, rather than counting on a calendar. That's what lets it handle irregular month lengths, leap years, and daylight saving transitions correctly instead of quietly getting them wrong. If a time you enter doesn't exist, or happens twice because of a clock change, it's flagged rather than silently miscalculated.
Learn More
The sections below go deeper on how each mode works and the edge cases it handles. Expand any of them for more detail.
How to use each mode
Date & Time mode — Enter a start date and time and an end date and time. Optionally set a different time zone on each side under "Time zone (optional)" if the two ends are in different locations. Select Calculate Difference for a full years, months, days, hours, minutes, and seconds breakdown, plus totals in weeks, days, hours, minutes, and seconds.
Dates Only mode — Enter a start date and an end date. Check "Include end date" if both endpoints should count toward the total, such as a rental period that includes the move-in day. Select Calculate Difference for the total day count and total weeks, alongside a years, months, and days breakdown.
Add / Subtract mode — Enter a start date, choose Add or Subtract, enter an amount, and choose whether it means days, weeks, months, or years. Select Calculate Date for the resulting date and its day of the week. Adding or subtracting months or years lands on the same day in the target month when possible, and falls back to the last valid day of that month when it doesn't exist — adding a month to January 31, for example, lands on February 28, or the 29th in a leap year.
Shortcuts — Today and Now buttons fill in the current date or time with one tap; Tomorrow, next to the end date, sets it one day ahead; Swap flips the start and end values. Once a result appears, Copy Result puts a plain-text summary on your clipboard, and Share opens your device's share options.
Why manual date counting goes wrong
Counting days by hand runs into a few consistent problems.
Months aren't the same length. February has 28 days most years and 29 in a leap year; April, June, September, and November have 30; the rest have 31. Assuming every month behaves like the last one is the most common source of a wrong date.
Leap years follow an exception most people don't remember: a year divisible by 4 is a leap year, except century years, which are only leap years if divisible by 400. 2000 was a leap year; 1900 wasn't. Any calculation spanning several years can land a day off if this isn't accounted for.
Whether the first day counts is a matter of convention, not math. A lease usually counts the move-in day; a countdown usually doesn't. That's why this calculator has an explicit "include end date" toggle instead of guessing.
Daylight saving changes make a day 23 or 25 hours long instead of 24. This rarely affects a plain day count, but it can throw off an hours-and-minutes total if the span you're measuring crosses the transition. This calculator also checks for two specific edge cases: a time that doesn't exist because clocks skipped over it, and a time that happens twice because clocks repeated it — both get flagged instead of silently producing a result that's an hour off.
As a sanity check on any result: dividing a day count by 30 gives a rough month estimate, and by 365 a rough year estimate. If the exact answer looks wildly different from that, it's worth double-checking the year you entered — a typo there is the easiest way to get a result that's off by a full year without looking obviously wrong.
Calculating hours, minutes, and timesheets
Comparing two clock times is subtraction with one added wrinkle: clock time resets at midnight. If an end time is earlier than the start time — an overnight shift running from 10 PM to 6 AM, for example — the calculation needs to recognize the day rolled over rather than returning a negative number. Date & Time mode handles that automatically.
For payroll, results are usually needed two ways: as hours and minutes (8 hours 30 minutes) and as a decimal (8.5 hours), since decimal hours multiply cleanly against an hourly rate. To account for an unpaid lunch or other break, subtract its total length from the raw span — a 9-hour shift with a 30-minute lunch pays out at 8 hours 30 minutes.
A few common examples:
| Start | End | Total | With a 30-minute break |
|---|
| 9:45 AM | 2:30 PM | 4h 45m | 4h 15m |
| 7:30 AM | 4:30 PM | 9h | 8h 30m |
| 8:00 AM | 5:00 PM | 9h | 8h 30m |
Doing the same math in Excel or Google Sheets
Spreadsheets store dates as plain numbers, which is why simple subtraction works: =B2-A2 returns the number of days between two date cells (format the result as a number, not a date, or it'll display oddly).
For a years/months/days breakdown, DATEDIF is the standard formula: =DATEDIF(A2,B2,"y") for years, "ym" for remaining months, "md" for remaining days.
For business days only, excluding weekends, NETWORKDAYS (or NETWORKDAYS.INTL for custom weekend patterns) does the job, and can exclude a supplied holiday list too.
All of this works identically in Google Sheets, which uses the same date-serial-number system and the same function names — Sheets tends to be a little more forgiving about how a typed date is interpreted.
Time zones and scheduling across locations
The time zone fields apply the correct offset to whatever date and time you enter on each side, including whether that zone currently observes daylight saving time — the gap between two zones isn't always constant year-round. It's an offset applied to the difference calculation, not a standalone converter for turning one specific moment into what it reads as elsewhere.
Two zones that are five hours apart in January might not be five hours apart in July, since not every country observes daylight saving, and the ones that do rarely start and end it on the same dates. For a recurring meeting across time zones, it's worth rechecking the offset for the actual date rather than reusing one worked out months earlier.
Date formats vary by country too — day before month across most of the world, month before day in the United States, year first under the ISO standard used by software. Misreading 03/04 as March 4 instead of April 3 is a common, avoidable mistake once you know to check the format first.
Frequently Asked Questions
How to Calculate Time From Two Dates
How to calculate time between two dates?
Convert both dates to a single number of days since a fixed reference point, then subtract the earlier one from the later one. That gives you the exact calendar-day count. From there you can convert into weeks, months, or years for a calendar-style breakdown, or apply a business-day rule if weekends and holidays need to be excluded.
How to calculate time in Excel between two dates?
Subtract the earlier date cell from the later one (=B2-A2) for a day count, or use DATEDIF with the "y", "ym", and "md" arguments together for a years, months, and days breakdown. Format the result cell as a number, not a date, or Excel will display it incorrectly.
Is there a formula to calculate time?
Yes. For dates, it's simple subtraction once both dates are converted to a common numeric scale. For clock times, it's the same subtraction, with 24 hours added to the end time whenever the calculation crosses midnight, so the result never comes out negative.
How to Calculate Time and Day
How to calculate time in a day?
Add up the hours and minutes between a start point and an end point within the same 24-hour period, using subtraction after converting both times to a 24-hour scale. If the day includes unpaid breaks, subtract those separately once the raw total is known.
How many hours is 9:45 to 2:30?
From 9:45 AM to 2:30 PM is 4 hours and 45 minutes. Subtract a 30-minute break, as would be typical for a short shift, and the paid total comes to 4 hours 15 minutes.
How Do I Calculate the Time Between Two Times
How to figure out time between two times?
Convert both times to 24-hour format, add 24 hours to the later time if it falls numerically before the earlier one (meaning the span crosses midnight), then subtract. The result converts cleanly into hours and minutes or decimal hours, depending on what you need it for.
How to calculate total time between two times in Excel?
Enter both times in a recognized time format, then subtract the earlier cell from the later one. Format the result cell using a custom time format such as [h]:mm so totals over 24 hours display correctly instead of resetting to zero.
How to calculate time multiply?
First find the duration as a decimal number of hours (7.5 rather than 7:30, for example), then multiply that decimal by whatever rate or factor applies, such as an hourly wage. Multiplying the decimal form avoids the errors that come from multiplying hours and minutes directly.
What Is the Correct Way to Calculate Time
How is time actually calculated?
Both dates and clock times are converted into a single continuous numeric scale first: days since a reference point for dates, hours or minutes past midnight for clock times. That conversion allows a straightforward subtraction to produce the gap between them, sidestepping the irregular lengths of months and the midnight reset of the clock.
What is the best way to manually calculate hours?
Convert both times to 24-hour format first, then subtract them as hours and minutes, borrowing 60 minutes from the hours column if the end minutes are smaller than the start minutes. Subtract any unpaid break time last, once the raw total is known.
How many hours from 7:30 till 4:30?
From 7:30 AM to 4:30 PM is 9 hours. With a typical 30-minute lunch break subtracted, the payable total is 8 hours 30 minutes.
How many hours is 8am to 5pm with lunch?
From 8:00 AM to 5:00 PM is 9 hours. Subtracting a standard 30-minute lunch break brings the payable total to 8 hours 30 minutes; a full one-hour lunch brings it down to 8 hours. Doing this kind of math by hand isn't complicated in principle, but it's full of small exceptions: months of different lengths, leap years, midnight crossings, time zone offsets, and the difference between calendar days and working days. Any one of those details is enough to throw off a hand calculation by a day or an hour, which is why a dedicated tool is worth using even when the question looks simple. Whatever the specific question, the number of days until a deadline, the hours on a timesheet, or the date ninety days from today, the same approach applies: convert everything to a consistent numeric scale first, then let the subtraction do the work.