How Many Hours Between Two Times? (With Examples)

"How many hours is 9:15 to 5:45?" "My shift is 10 PM to 6 AM — is that eight hours?" "How do I write 7 hours 30 minutes on a timesheet?" Time-between questions look trivial until the times cross noon, cross midnight, or include minutes that don't subtract cleanly (you can't take 4:45 minus 9:15 directly).

The fix is to stop working with clock times and start working with minutes since midnight. This guide shows the method, worked examples for day and overnight spans, break subtraction, and the decimal-hours table every timesheet expects.

The method: convert to minutes since midnight, subtract, convert back

Step 3's "add 1440" is what makes overnight shifts easy: 10 PM to 6 AM looks negative (360 − 1320 = −960) until you add a day's worth of minutes, giving 480 minutes = 8 hours.

Worked example: 9:15 AM to 5:45 PM

• Start: 9 × 60 + 15 = 555 minutes
• End: 17 × 60 + 45 = 1065 minutes (5:45 PM is 17:45 on a 24-hour clock)
• Difference: 1065 − 555 = 510 minutes
• Convert: 510 ÷ 60 = 8 hours 30 minutes = 8.5 decimal hours

The 24-hour clock conversion for the end time matters: 5:45 as "5 × 60 + 45 = 345" would give a negative difference, which is your signal that you treated an afternoon time as a morning one. After noon, add 12 to the hour (12 PM stays 12; 12 AM becomes 0).

Worked example: the overnight shift, 10 PM to 6 AM

• Start: 22 × 60 = 1320 minutes
• End: 6 × 60 = 360 minutes
• Difference: 360 − 1320 = −960 → negative, so add 1440 → 480 minutes = exactly 8 hours

An overnight span always produces a negative raw difference — that “negative” isn't an error, it's the code for "crossed midnight." One caution: if a shift can be longer than 24 hours, minute-since-midnight math alone can't distinguish 8 hours from 32; note the day along with the time for spans that long.

Subtracting breaks: the timesheet case

Worked time usually excludes unpaid breaks. Take 9:00 AM → 5:00 PM with a 30-minute lunch:

• Gross span: 8 hours 0 minutes
• Minus lunch: 8 h − 0 h 30 m = 7 hours 30 minutes = 7.5 hours

Subtract breaks at the end, from the finished span — don't try to remove them from the clock times themselves. Two breaks of 15 minutes each subtract the same 0.5 hours as one 30-minute lunch.

The decimal-hours table timesheets expect

Payroll systems almost always want decimal hours, not hours and minutes. The conversion is minutes ÷ 60:

So 7 hours 30 minutes goes on the timesheet as 7.5, and 8 hours 45 minutes as 8.75. A common rounding rule (nearest quarter hour) makes :08/:53-type values snap to the nearest 0.25 — check which rounding your payroll uses before you submit.

AM/PM and the 24-hour clock, quickly

• 12:00 AM (midnight) = 0:00 · 12:00 PM (noon) = 12:00
• 1 PM to 11 PM = 13:00 to 23:00 (add 12 to the hour)
• 1 AM to 11 AM = 1:00 to 11:00 (unchanged)

The single most common AM/PM slip: typing 12 when you mean 0. Midnight is hour 0, noon is hour 12 — that asymmetry is why "12:30 AM to 1:00 AM" is 30 minutes (0:30 → 1:00), not eleven and a half hours.

Common mistakes

• Subtracting clock times directly.5:45 − 9:15 isn't a legal operation — convert to minutes first, every time.
• Afternoon times left on the 12-hour clock. 5:45 PM must become 17:45 (1065 minutes) before subtracting; otherwise you get a negative number that hides the real bug.
• Writing 7:30 on a timesheet. Payroll reads colon notation inconsistently — 7:30 might be entered as 7.30 hours. Write 7.5.
• Forgetting unpaid breaks. Gross span and paid span differ by the break total; subtract it explicitly.
• Time zones for meetings."How many hours until the 3 PM call?" only works if the call time is in your zone. For cross-zone scheduling, our time zone converter shows one moment across every zone at once.

Frequently Asked Questions

How do I calculate hours between two times across midnight?

Convert both times to minutes since midnight, subtract, and if the result is negative add 1440 (one full day). 10 PM → 6 AM: 360 − 1320 = −960; −960 + 1440 = 480 minutes = 8 hours.

How many hours is a 9-to-5 workday?

Eight hours gross. With a 30-minute unpaid lunch it's 7.5 paid hours (7 hours 30 minutes); with two 15-minute breaks and no lunch, also 7.5. That's why full-time salary math assumes 2,080 paid hours per year (40 × 52) but actual scheduled hours at work are higher.

How do I convert hours and minutes to just hours?

Divide the minutes by 60 and add to the hours: 8 h 45 m = 8 + 45/60 = 8.75 hours. The table above lists every 5-minute value; 15 minutes is 0.25, 30 is 0.5, 45 is 0.75.

Is 12 AM midnight or noon?

12 AM is midnight (the start of the day, hour 0). 12 PM is noon (hour 12). If a deadline says "12 AM Tuesday," it means the night from Monday into Tuesday — when it matters, confirm or use 24-hour notation (00:00 vs 12:00).

What's the difference between hours elapsed and business hours?

Hours elapsed counts every hour on the clock (9 AM Monday → 9 AM Tuesday = 24 hours). Business hours usually means 9 AM–5 PM Mon–Fri only, so the same span contains just 8 business hours. Delivery promises typically use business hours or business days — see our working days guide for that counting method.

Related Calculators

• Time Calculator — Add or subtract hours and minutes from any start time
• Time Card Calculator — Full week of shifts → decimal hours and pay
• How to Calculate Work Hours on a Time Card — The complete timesheet method, breaks included
• Date Calculator — For spans measured in days rather than hours