Free · Time converters 🕰️

Milliseconds, Seconds & Compound Duration Table

Convert elapsed durations across milliseconds, seconds, larger fixed units and compound time notation.

  • 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

1:02:03 in hours:minutes:seconds is 3,723 seconds or 3,723,000 milliseconds. The colon separates components; it is not a decimal point.

Seconds = milliseconds ÷ 1,000; seconds = 3,600 × hours + 60 × minutes + seconds component

Worked example

Enter these known values and leave the other values blank.

Compound duration in selected units
1:02:03 hrs / min / sec
Milliseconds
3723000 ms
Seconds
3723 sec
Fixed Julian years
0.00011797 yrs
Fixed mean months
0.0014157 mos
Weeks
0.006156 wks
Days
0.04309 days
Hours
1.0342 hrs
Minutes
62.05 min

Assumptions and limitations

  • This converts elapsed duration, not a clock time, date or time-zone offset. No daylight-saving transitions or leap seconds are modeled.
  • A day is exactly 24 hours, a week 7 days, a Julian year 365.25 days, and the mean month one twelfth of that year (30.4375 days). Calendar months do not all have that length.
  • Use colon-separated components in their selected order. In hours/minutes/seconds mode, 1:30:00 means 90 minutes; decimal 1.5 in a plain hours field represents the same duration.
  • A leading minus sign applies to the entire compound duration. Zero and negative values can represent elapsed-time differences; they are not dates before or after a calendar event.

Common questions

Can I convert in the opposite direction?

Yes. Enter the known value in any editable field. The other representations update in their selected units; changing a unit preserves the physical quantity.

Can I use the month result for an exact date interval?

No. It uses a fixed 30.4375-day duration. An exact calendar interval requires specific dates and calendar rules.

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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