Free · Unit conversions

Hours, Seconds & Hours:Minutes:Seconds

Convert nonnegative hours, seconds and compound time with reverse entry and exact factors.

  • Formula & worked example
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Calculator inputs

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How to use this calculator

  1. Enter the known values in the units shown. Results update as you type.
  2. Where results are editable, change one to solve backwards. Lock a value to hold it fixed.
  3. Use the worked example to check the method. Reset restores the starting fields.

Private by default

Inputs and results stay in this browser tab. Bookify does not upload or store the values you enter.

Formula and method

1.5 hours equal 5,400 seconds or 1:30:00. Enter compound time with colons rather than interpreting it as a decimal.

Seconds = hours × 3,600; compound seconds = 3,600h + 60m + s

Worked example

Enter these known values and leave the other values blank.

Duration in hours
1.5 hrs
Duration in seconds
5400 sec
Hours:minutes:seconds
1:30:0 hrs / min / sec

Assumptions and limitations

  • Durations are nonnegative. One hour is exactly 3,600 seconds.
  • Compound input is hours:minutes:seconds. The display can round fractional seconds; the calculation retains underlying precision.
  • This is elapsed-time arithmetic without dates, time zones or clock-change rules.

Common questions

Is 1:30 the same as 1.30 hours?

No. For this three-part compound field use 1:30:00, which equals 1.5 hours. Decimal 1.30 hours equals 1 hour 18 minutes.

Can I enter seconds first?

Yes. Enter a seconds value to calculate decimal hours and compound time.

References

The calculation equations, inverse formulas, units, and input rules were imported from this source. Bookify provides the interface and equation solver.

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