TCalc is a calculator that understands time. Ordinary calculators work in decimals, so 1.30 means one and a third — not one hour thirty. That single mismatch is why adding shifts, subtracting dates or carrying frames by hand goes wrong so often.
Type an expression the way you would say it out loud. Durations, clock times, dates, SMPTE timecodes and UNIX timestamps are all first-class values, and the calculator keeps track of which is which — so it knows that a duration added to a clock time produces a time of day, while one date minus another produces a span.
Results can be shown in 15 output formats — compact time, decimal hours, work days, ISO 8601, epoch seconds and frame-accurate timecode among them — and you can switch between them without retyping the expression.
Hours worked: clock-out minus clock-in minus an unpaid break.
A duration added to a clock time returns a time of day, not a number.
Days between now and a fixed date.
A weekly total, switched to decimal hours for payroll.
Timecode plus 200 frames, carried correctly at 24 fps.
The calculator ships with preset layouts for the professions that do time maths daily. Each page below explains the rules that trade actually works under and the expressions that match them.