Hours Calculator

Turning a start and end time into payable hours

Every timesheet, freelance invoice, and shift roster eventually reduces to the same small piece of arithmetic: how much time actually elapsed between a start and an end, minus whatever unpaid gap sat in the middle, expressed in a format a spreadsheet or payroll system can multiply by an hourly rate. That last part matters more than it looks — hours and minutes don't multiply cleanly (7 hours 30 minutes times $18 isn't "7.30 × 18"), so the duration has to be converted to a decimal before it's useful for pay.

This calculator covers both directions of that problem: measuring the gap between two clock times — including a shift that runs past midnight — and projecting a new clock time by adding or subtracting a duration. It's built for hourly employees closing out a shift, contractors billing by the hour, warehouse or hospital staff on overnight rotations, and anyone reconstructing "what time will it be six hours and fifteen minutes from now."

Reading the inputs correctly

1. In the Between two times tab, set the start time and end time exactly as they appear on the schedule or clock-in system — no need to guess whether a shift crosses midnight, the tool detects that from the values alone.
2. Enter unpaid break minutes as a single number (e.g. a 30-minute lunch). If a shift has two breaks, add their minutes together before typing them in; the field subtracts one lump sum from the gross duration.
3. In the Add or subtract time tab, pick a base time, choose the operation, then enter hours and minutes separately — this is for projecting forward or backward from a known clock time rather than measuring a gap.

The arithmetic underneath

Worked examples

Minutes to decimal hours, at a glance

Common mistakes to avoid

• Split shifts: if a schedule has two separate work blocks (e.g. 09:00–13:00 and 15:00–19:00), calculate each block separately and add the results — entering the full 09:00–19:00 span with a single break understates the true unpaid gap.
• Reading decimal hours as minutes: 7.5 decimal hours is 7 hours 30 minutes, not 7 hours 5 minutes — the digits after the decimal point are a fraction of 60, not a minute count.
• Assuming any PM-to-AM entry rolls over: the midnight rollover only triggers when the end time is numerically earlier than the start time. A shift from 14:00 to 22:00 doesn't roll over even though it ends in the evening; only genuinely overnight spans (like 23:15 to 07:00) do.
• Applying employer rounding rules mentally first: some workplaces round clock times to the nearest 5 or 15 minutes before pay calculation. Enter the raw clock-in/clock-out times here, then apply your employer's rounding policy to the result — mixing the two produces a duration that matches neither.

What this tool doesn't cover

This is a plain clock-arithmetic tool, not a payroll or compliance system. It doesn't apply overtime multipliers, doesn't know your employer's or jurisdiction's break requirements or rounding conventions, and doesn't account for daylight saving time transitions (a spring-forward or fall-back night is technically 23 or 25 hours long rather than 24). For pay disputes or compliance questions, treat the decimal-hours figure as a starting point and check it against your employer's timekeeping policy or local labor rules.