This time calculator adds and subtracts durations — hours, minutes and seconds — carrying cleanly across the 60-minute and 24-hour boundaries that make hand arithmetic annoying. Work shifts, project hours, workout splits, travel legs: add them up here.

First duration

Operation

Second duration

Total–
In Days + Time–
Decimal Hours–
Total Seconds–

Why Time Arithmetic Trips People Up

Time is not decimal: 60 seconds make a minute, 60 minutes make an hour, 24 hours make a day. Adding 7 h 45 min + 2 h 30 min in your head means carrying at 60, not 100 — 10 h 15 min, not “9 h 75 min.” Payroll clerks, pilots logging flight time, editors summing video footage and anyone billing by the hour meet this daily. This calculator is part of our Everyday Life Calculators collection; for calendar dates and business days, use the Date Calculator.

Worked Examples (Verified)

  • Adding work shifts: 7 h 45 min + 2 h 30 min = 10 h 15 min (10.25 decimal hours — the number payroll wants).
  • Crossing a day: 20 h + 9 h 30 min = 29 h 30 min = 1 day, 5 h 30 min.
  • Subtracting: 5 h 10 min − 2 h 45 min = 2 h 25 min — borrowing an hour as 60 minutes, done for you.
  • Seconds carry too: 45 min 50 s + 20 min 30 s = 1 h 6 min 20 s.

Time Math in Real Life

  • Timesheets and billing: decimal hours (0.25 = 15 min) are how invoices add up — the decimal-hours card exists for exactly this.
  • Travel: legs, layovers and time-zone offsets are duration arithmetic; the date itself belongs to the Date Calculator.
  • Media and sport: episode runtimes, race splits and interval timers all sum in base-60.
  • The classic trap: 1.5 hours is 1 h 30 min, not 1 h 50 min. Decimal and clock forms look alike and are not — convert deliberately.

Related Tools

Frequently Asked Questions

How do I add hours and minutes?

Add each unit, then carry: every 60 minutes become an hour, every 60 seconds a minute. 2 h 50 min + 1 h 30 min → 3 h 80 min → 4 h 20 min.

How do I convert minutes to decimal hours?

Divide by 60: 15 min = 0.25 h, 45 min = 0.75 h. The calculator’s Decimal Hours card shows the full duration in this payroll-friendly form.

How do I subtract times?

Subtract each unit, borrowing 60 from the next unit up when a column would go negative — the calculator handles borrowing automatically.

How many seconds are in a day?

86,400 — 24 × 60 × 60. The Total Seconds card converts any duration instantly.

What if my durations span multiple days?

Enter total hours freely (e.g., 50 hours) — the Days + Time card breaks the result into days and clock time.

Is this time calculator free?

Yes — free, instant, no sign-up.