Free · Time and date calculators ⏳

Session Duration Total & Decimal-Hour Converter

Total up to twenty hours-and-minutes durations, with a separate decimal-hours and minutes conversion pair.

  • Formula & worked example
  • Private in your browser
  • No signup
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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

Adding 1:30 and 2:45 gives 4:15, or 255 minutes. Separately, 1.5 decimal hours equals 90 minutes.

Total = sum of twenty duration entries; minutes = decimal hours × 60

Worked example

Enter these known values and leave the other values blank.

Time 1
1:30 hrs / min
Time 2
2:45 hrs / min
Separate decimal-hour conversion
1.5 hrs
Sum of all retained durations
4:15 hrs / min
Separate minute conversion
90 min

Assumptions and limitations

  • Use hours:minutes in the default duration fields. A decimal-hour value is a different notation: 1.5 hours is 1:30, not 1:50.
  • The decimal-hours conversion pair is independent of the duration sum. Enter a value in that pair to convert it; it does not automatically mirror the summed duration.
  • Reducing the row selector preserves nonzero later values, which remain visible and included. Clear a value to remove it from the sum.
  • Signed durations are supported. This arithmetic does not determine clock-time intervals, calendar months, breaks or daylight-saving adjustments.

Common questions

Does changing the row count delete entries?

No. Nonzero later entries remain visible and counted. Clear a row explicitly when it should no longer contribute.

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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