Time Duration Calculators

Add and Subtract Times, Hours Between Times, Decimal Hours and Time Unit Converter

Duration calculators for adding up hours and minutes, finding the hours between two clock times, turning 7:45 into 7.75 decimal hours and back, and converting between seconds, minutes, hours, days and weeks.

Every Durations tool

Decimal Hours Converter

Convert 7:45 to 7.75 hours and back again.

Hours Calculator

Hours between two times, minus breaks, with overnight shifts.

Time Calculator

Add and subtract hours, minutes and seconds in one line.

Hours To Minutes Converter

Convert between seconds, minutes, hours, days and weeks.

Why durations need their own maths

Time is counted in sixties, not tens, so 1:50 plus 0:20 is 2:10, not 1:70. These calculators reduce every duration to whole seconds before adding, which avoids the rounding drift that builds up when you add decimal hours one at a time in a spreadsheet.

Clock times and decimal hours

Payroll and billing systems usually want decimal hours, while people think in hours and minutes. Fifteen minutes is 0.25 hours and twenty minutes is 0.33, so converting before you multiply by a pay rate keeps the total right on every timesheet and invoice.