How to Calculate Hours and Minutes Between Two Times
Reviewed by Jerry Croteau, Founder & Editor
Table of Contents
I was standing in the lumber aisle doing math on my phone and nothing was adding up
I’d started a timer at 7:45, I stopped it at 2:10, and my brain kept insisting that was “about 6 hours.” Which… no. Not even close. I stared at the screen, did the little finger-counting thing like a caveman, and still got different answers depending on whether I rounded first or subtracted first.
So yeah, if you’re trying to calculate hours and minutes between two times, you’re not alone.
And the annoying part is it’s easy once you do it the same way every time.
What you’re actually trying to measure (and why people mess it up)
You’re not subtracting “2:10 minus 7:45” like it’s normal subtraction. You’re measuring elapsed time, which is basically “how many minutes happened between point A and point B,” and then you translate those minutes back into hours and minutes.
Most mistakes come from one of three things: you forget to “borrow” an hour when the end minutes are smaller than the start minutes, you cross noon/midnight and don’t notice, or you mix 12-hour time with 24-hour time and end up arguing with yourself. (I’ve done all three, and I’ve nodded like I understood what I did wrong. I didn’t.)
So here’s the move: convert to minutes, subtract, convert back.
That’s it. It’s not fancy. It just works.
The quick “do it by hand” method (works on a sticky note)
If you’re in a hurry and don’t want to convert everything to minutes, you can do the borrow method. It’s the same math, just done in a way your brain recognizes.
Example: Start 7:45, End 14:10 (that’s 2:10 PM in 24-hour time).
- Minutes: 10 − 45 doesn’t work, so you borrow 1 hour from 14 hours.
- Now you have 13 hours and 70 minutes.
- Minutes: 70 − 45 = 25 minutes
- Hours: 13 − 7 = 6 hours
Answer: 6 hours 25 minutes.
That’s the same result you’d get with the total-minutes formula, just less button-pushing.
But if you’re dealing with payroll, job logs, travel time, or anything where you can’t afford to be “kinda close,” I’d stick with the minutes conversion. It’s boring, but boring is accurate.
Worked examples you can steal (including midnight)
I’ll give you a few real-world ones, because this is where it clicks. You’ll see the same pattern every time: convert, subtract, convert back. And if you cross midnight, you tack on a day’s worth of minutes (1,440) to the end before you subtract.
Example 1: Lunch break tracking
Start 11:35, End 13:05.
- Start minutes = 11×60 + 35 = 695
- End minutes = 13×60 + 5 = 785
- Difference = 785 − 695 = 90 minutes
- Convert back: 90 ÷ 60 = 1 hour, remainder 30 minutes
Answer: 1 hour 30 minutes.
Example 2: You forgot to stop the timer until later
Start 8:50, End 12:15.
- Start = 8×60 + 50 = 530
- End = 12×60 + 15 = 735
- Diff = 205 minutes
- 205 minutes = 3 hours (180) + 25 minutes
Answer: 3 hours 25 minutes.
Example 3: Overnight shift (crossing midnight)
Start 22:40 (10:40 PM), End 2:10 (2:10 AM next day).
- Start = 22×60 + 40 = 1,360
- End = 2×60 + 10 = 130
- End is “smaller” because it’s the next day, so add 1,440: 130 + 1,440 = 1,570
- Diff = 1,570 − 1,360 = 210 minutes
- 210 minutes = 3 hours 30 minutes
Answer: 3 hours 30 minutes.
That midnight trick is the one that makes people swear the math is broken. It’s not broken. You just changed days and didn’t tell the equation.
So why does everyone get this wrong? Because time looks like base-10 math but it’s base-60 in the minutes column, and your brain wants to treat 2:10 like “two point one zero.” It isn’t.
And yeah, if you’re doing this a lot, don’t keep re-learning it. Use a calculator and move on with your day.
Here are a few that I lean on depending on what I’m trying to do:
A small cheat table (because you’ll see these numbers a lot)
If you’ve ever looked at a timesheet and seen stuff like 0:15, 0:30, 0:45 everywhere… same. These are the ones that show up constantly. And if you’re converting to decimal hours for payroll, these are the usual suspects.
| Minutes | Hours:Minutes | Decimal Hours (roughly) |
|---|---|---|
| 15 | 0:15 | 0.25 |
| 30 | 0:30 | 0.50 |
| 45 | 0:45 | 0.75 |
| 75 | 1:15 | 1.25 |
| 90 | 1:30 | 1.50 |
And just so it’s said out loud: a quarter hour is 15 minutes. That’s it — 15 minutes. Not “kinda around 10-ish.”
But don’t get cute with decimals if your system wants hours and minutes. I’ve seen people write 7.30 hours meaning “7 hours 30 minutes” and the payroll software reads it as 7 hours 18 minutes (because 0.30 of an hour is 18 minutes). That’s a real headache!
FAQ
What if my end time is earlier than my start time?
Usually that means you crossed midnight. Add 24 hours (1,440 minutes) to the end time after converting it to minutes, then subtract like normal.
How do I convert the result into decimal hours for payroll?
Take total minutes and divide by 60.
Example: 6 hours 25 minutes = (6×60 + 25) = 385 minutes. 385 ÷ 60 = 6.4167 hours (roughly). If you need that fast, I use
Is there a “fast mental math” way without converting everything?
- Subtract hours.
- Subtract minutes.
- If minutes go negative, add 60 minutes and subtract 1 hour.
It’s basically the borrow method. Works great until you’re tired or distracted (which is… most of the time).
If you’re doing one time span, do it by hand and move on. If you’re doing ten of them, don’t be a hero—use the calculator and keep the job moving.
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