Time Duration Calculator

How the time duration is calculated

The calculator measures the time between a start and end time, subtracts your unpaid break, and reports the result in hours and minutes as well as decimal hours — the format payroll systems expect. It can round payable time, repeat the shift total, and if the end time is earlier than the start, it assumes the shift crosses midnight and adds 24 hours.

Formulas

Duration = end − start (+ 24 h if overnight) − break

Payable time = rounded duration, if a rounding interval is selected

Decimal hours = total minutes ÷ 60

Pay = regular hours × rate + overtime hours × rate × multiplier

Worked example

A shift from 09:00 to 17:30 with a 30-minute break and no rounding: 8.5 hours minus 0.5 = 8 hours (8.0 decimal hours). At $25/hour with overtime after 8 hours, all 8 hours are regular time: $200. Stretch the shift to 19:00 and the extra 1.5 hours are paid at 1.5× — 8 × 25 + 1.5 × 37.50 = $256.25.

Minutes to decimal hours

Payroll and invoicing run on decimal hours; clocks do not. The whole minute range, so nothing has to be worked out by hand mid-timesheet.

The three that get mistyped most often are 20 minutes (0.33, not 0.20), 40 minutes (0.67, not 0.40) and 50 minutes (0.83, not 0.50) — the ones where the minute figure looks like it could pass as a decimal.

Billing increments

Professional time is usually billed in fixed blocks rather than to the minute, and the block size changes the total materially. A six-minute increment is one tenth of an hour, which is why legal and consultancy timesheets are kept in tenths.

Rounded up, that seven-minute call costs the client 0.2 hours on a six-minute grid and 0.5 hours on a half-hour grid — two and a half times as much for identical work. Twenty short calls a week is where the difference stops being trivia.

Daily and weekly overtime thresholds

Overtime can trigger on the day, on the week, or both, and the rules are jurisdictional. Under the US federal standard it is weekly: time over 40 hours in a workweek is paid at 1.5×, with no daily threshold at all. Several states add a daily one — California pays 1.5× beyond 8 hours in a day and 2× beyond 12. The UK has no statutory overtime premium; it is whatever the contract says, subject to the weekly average working-time limit.

The practical consequence is that four ten-hour days can be entirely ordinary time in one place and eight hours of overtime in another, for the same 40-hour week. Set the calculator's threshold to the rule that actually applies to you rather than the default.

Overnight shifts and crossing midnight

When the end time is earlier than the start — a shift from 22:00 to 06:00, for example — the calculator assumes the clock passed midnight and adds 24 hours, giving 8 hours rather than a negative result. This covers night shifts and late hospitality or healthcare hours without you having to split the entry across two days.

Why rounding is applied

Many payroll systems round clock time to a fixed interval — often the nearest 5, 6, or 15 minutes — so the payable total lines up with a standard pay grid. Rounding to the nearest quarter-hour is common and, done to the nearest interval, is broadly neutral over time because minutes rounded down balance those rounded up. Set the rounding to match your employer's rule so the decimal hours you report agree with the paycheck.

To annualize your rate across a full schedule, see the salary hourly/yearly calculator.