Time Duration Calculator

Built for timesheets: it handles overnight shifts, subtracts breaks, and gives the decimal hours that payroll systems expect.

Handling shifts that cross midnight

The naive calculation — end minus start — produces a negative number for any overnight shift. 22:30 to 06:15 gives −975 minutes, which is obviously wrong.

Adding 1440 minutes (24 hours) gives the correct 465 minutes, or 7 hours 45 minutes. This calculator applies that correction automatically and tells you when it has done so.

The one ambiguity it cannot resolve: a start and end time that are identical could mean zero duration or a full 24 hours. This tool treats it as 24 hours, since a zero-length shift is rarely what anyone means.

Decimal hours and why payroll uses them

Payroll systems almost universally work in decimal hours rather than hours and minutes, because multiplying 7:45 by a pay rate is awkward while multiplying 7.75 is trivial.

The classic mistake is writing 7 hours 30 minutes as 7.30 rather than 7.50, which underpays by 12 minutes on every shift. Over a year of five shifts a week that is more than 25 hours.

Breaks and rest entitlements

Whether a break is paid varies by employer and jurisdiction, but the rest entitlement itself is often a legal minimum rather than a courtesy. In the UK, workers over 18 are entitled to an uninterrupted 20-minute rest break when working more than six hours, at least 11 hours of rest between working days, and a weekly rest period. The EU Working Time Directive sets comparable minima across member states, and many US states mandate meal and rest breaks.

Night work frequently carries additional protections and, in many roles, a shift premium. If you are regularly working overnight shifts, it is worth checking what your contract and your local law actually provide for.