THE NUMBERS, EXPLAINED
How to use this calculator.
An earlier end time is treated as the next day. Equal times mean zero hours, not 24. This is a wall-clock duration without DST adjustments.
Start with your inputs
Enter start time (hh:mm), end time (hh:mm). Keep amounts in the units shown on each field. The example is a starting point, not a recommended value.
| Input | Example value |
|---|---|
| Start time (HH:MM) | 22:00 |
| End time (HH:MM) | 06:00 |
A worked example
With the example inputs above, duration (hours) is 8. Change the inputs to explore your own scenario.
| Result | Example answer |
|---|---|
| Duration (hours) | 8 |
How this is calculated
Duration (hours)
((clockMinutes(b)-clockMinutes(a)+1440) rem 1440) ÷ 60
Symbols and units
- a
- Start time (HH:MM)
- b
- End time (HH:MM)
Use the units shown. A list keeps the order in which you enter its values. The symbol ^ means “raised to the power of”.
Calculation steps and notation
clockMinutes(HH:MM) = 60 × hours + minutes. It represents a wall-clock time within one day, without a date or timezone.
rem means the remainder after division; it is not a percentage sign.
Assumptions and limits
An earlier end time is treated as the next day. Equal times mean zero hours, not 24. This is a wall-clock duration without DST adjustments.
Calculations use the values you enter. Blank or invalid inputs show an error instead of silently substituting zero. Results are displayed to useful precision; calculations retain the underlying numeric precision.
Questions about this tool
What does the result tell me?
Duration (hours). The result applies to the method and inputs described above. Check the units and assumptions before using it in a decision.
Why might another calculator differ?
Differences in units, rounding, timing or model definitions can produce different answers. Compare the input definitions and the method, rather than only the final number. For this tool: An earlier end time is treated as the next day. Equal times mean zero hours, not 24. This is a wall-clock duration without DST adjustments.
Are my inputs stored or sent to AI?
Calculations on this page happen in your browser. The separate AI question finder sends its submitted conversation to OpenAI; these calculator fields are not sent. Favourites and recent tool names are stored locally. A shared link contains the inputs you choose to include.
Review status
Software example and browser checks are recorded in our quality report. No external expert review is claimed. Created with coding assistance; calculations run as ordinary browser code.
Read the quality report →