Time Calculator
This time calculator adds or subtracts hours, minutes, and seconds, and it'll find the duration between two clock times too. Pick a mode, type your times, and you'll get the answer in clean h:m:s along with the total in decimal hours for a timesheet. The duration mode even crosses midnight, so an overnight shift counts correctly. It's free, private, and updates as you type.
- Add & subtract time
- Hours, minutes, seconds
- Duration between times
- Crosses midnight
- Decimal hours
Last updated July 23, 2026 60 sec = 1 min, 60 min = 1 hour Built and maintained by Muhammad Younus
If the end is earlier than the start, the tool counts it as overnight and adds 24 hours.
Add and subtract take hours, minutes, and seconds. Time between takes two clock times.
2:45:00 + 1:30:00 = 4:15:00
How does a time calculator work?
Time isn't base ten, so you can't just add the numbers and stop. Sixty seconds make a minute and sixty minutes make an hour, so the trick is to carry across those boundaries. The clean way is to turn each time into total seconds, do the plus or minus, then convert back to hours, minutes, and seconds. That's exactly what this time calculator does, which is why 2 hours 45 minutes plus 1 hour 30 minutes lands on 4 hours 15 minutes rather than 3 hours 75. It'll also show the answer in decimal hours, since that's what a payroll sheet wants.
Adding 2:45 and 1:30 by hand
Here's the carry in action. It's the same method the tool runs, just spelled out:
- 1
Add the minutes45 minutes plus 30 minutes is 75 minutes, which is more than an hour.
- 2
Carry the hour75 minutes becomes 1 hour and 15 minutes, so you carry that hour over.
- 3
Add the hours2 hours plus 1 hour plus the carried hour is 4 hours.
- 4
Read the resultPutting it back together gives 4 hours and 15 minutes, or 4.25 in decimal.
Minutes to decimal hours
Here's how common minute amounts read in decimal hours, which is the format most timesheets and billing tools expect. If you're filling out a timecard, that's the column you'll want. The calculator shows this conversion for you on every result.
| Minutes | Decimal hour | Minutes | Decimal hour |
|---|---|---|---|
| 10 min | 0.17 | 35 min | 0.58 |
| 15 min | 0.25 | 40 min | 0.67 |
| 20 min | 0.33 | 45 min | 0.75 |
| 30 min | 0.50 | 50 min | 0.83 |
What time is it a set number of minutes later?
A lot of time questions aren't "how long is this," they're "what clock time do I land on." To find the time a gap later, add the minutes to the clock and carry an hour whenever the minutes pass 60. So 30 minutes after 1:15 is 1:45, and 30 minutes after 12:45 rolls over to 1:15. Going backward, you borrow: 15 minutes before 2:00 PM is 1:45 PM. Here are a few worked out:
- 30 minutes after 1:15 → 1:45 (the 15 minutes plus 30 lands on 45)
- 45 minutes after 12:40 → 1:25 (85 minutes carries one hour)
- 15 minutes before 2:00 PM → 1:45 PM (borrow from the hour)
To measure the gap between two clock times instead, use the time between mode above, which handles overnight spans too. If you need to add whole days rather than minutes, the date calculator adds or subtracts days from a date, and for logging paid hours the overtime calculator turns your total into regular and time-and-a-half pay.
Frequently asked questions
It's 1:45. Adding 30 minutes to 1:15 pushes the minutes from 15 up to 45 while the hour stays put, so you land on 1:45. Any time the minutes cross 60 you carry an hour, so 30 minutes after 12:45 rolls over to 1:15. To measure the gap the other way, drop the two clock times into the time between mode and read the hours and minutes.
It's 1:45 PM. Taking 15 minutes off 2:00 borrows from the hour, so 2:00 steps back to 1:45. Counting backward from a clock time works exactly like counting forward, just in reverse, and you borrow 60 minutes from the hour whenever the minutes would go below zero.
It's 2 hours and 45 minutes. From 1:30 to 4:00 is 2 hours 30 minutes, and the extra 15 minutes up to 4:15 tacks on a quarter hour. Switch to time between mode, enter 1:30 as the start and 4:15 as the end, and the tool shows 2:45 along with the total in decimal hours.
Add the seconds, the minutes, and the hours separately, then carry: every 60 seconds rolls into a minute and every 60 minutes rolls into an hour. So 2 hours 45 minutes plus 1 hour 30 minutes is 4 hours 15 minutes, because the 75 minutes carries one hour. This time calculator does the carrying for you, so you just type the two times and read the answer.
Line the two times up and take one from the other, borrowing when a column goes negative. If the seconds or minutes you're subtracting are larger, you borrow 60 from the column to the left, the same way you borrow 10 in normal subtraction. Switch the tool to subtract mode and it handles the borrowing, and it'll show a negative result if the second time is the larger one.
Pick the duration mode, enter a start and an end clock time, and you'll get the hours and minutes in between. If the end time is earlier than the start, the tool treats it as crossing midnight and adds 24 hours, so 10 PM to 6 AM reads as 8 hours. That's handy for shifts, sleep, travel, and anything that runs overnight.
Decimal hours write minutes as a fraction of an hour, which payroll and billing systems prefer. Fifteen minutes is 0.25, thirty is 0.5, and forty-five is 0.75, so 4 hours 15 minutes is 4.25 hours. The tool shows the decimal total next to the clock format, so you don't have to convert it yourself for a timesheet.
Yes. The add and subtract modes take hours, minutes, and seconds, so you can total lap times, cooking steps, or audio clips down to the second. The result normalizes properly, rolling 60 seconds into a minute and 60 minutes into an hour, and the totals row shows the whole span in seconds and minutes if that's the figure you need.
Yes on both. There's no sign-up, no limit, and nothing to install, since it runs right in your browser. Whatever you type stays on your device, so none of it gets sent anywhere. Bookmark the page and you'll have a quick way to add, subtract, or measure time whenever a task calls for it.
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