Calculate duration between times, convert decimal hours to hours and minutes or sum time durations with calculation steps.
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Inputs
Enter values
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Calculate DurationCompare start time and end time
iBeginning of the duration.
Beginning of the duration.
iEnd of the duration. If the end time is before the start time, it is calculated until the next day.
End of the duration. If the end time is before the start time, it is calculated until the next day.
Load example
For illustration only – your own calculation is what counts.
Explanation
How Hours Calculator works
The hours calculator compares times on a minute basis. The result is always displayed as an hours-and-minutes value.
Additionally, the calculator can convert decimal hours, convert hours and minutes to decimal hours, and sum multiple time durations.
DurationDuration = End time - Start time
Start and end are converted to minutes. If the end time is smaller, one day is added.
Decimal hours to minutesMinutes = Decimal hours x 60
The decimal value is converted to total minutes, rounded to the nearest whole minute, and then split into hours and minutes.
Hours and minutes to decimal hoursDecimal hours = (Hours x 60 + Minutes) / 60
First all values are combined into minutes, then divided by 60.
Add timesTotal duration = Time 1 + Time 2 + Time 3
The sum mode adds time durations. It does not add clock times and does not evaluate working time rules.
Knowledge
Distinguishing Time Duration, Decimal Hours and Minutes
Clock times, time durations and decimal hours are different representations of the same minute basis.
The hours calculator internally works with total minutes. This allows clean conversion between clock time differences, decimal hours and hours-minutes values.
Clock times like 08:15 describe a point in time during the day.
Time durations like 8 h 30 min describe a length.
Decimal hours like 8.5 h are practical for spreadsheets.
Working time with breaks belongs in the working time calculator.
Practice
Practical examples
For illustration only – your own calculation is what counts.
Duration Between Times
Start time and end time yield the time duration in hours, minutes and decimal hours.
Result: From 08:15 to 16:45 there are 8 h 30 min or 8.5 decimal hours.
Convert Decimal Hours
A decimal value like 7.5 hours is converted to hours and minutes.
Result: 7.5 decimal hours equal 7 h 30 min.
Hours and Minutes as Decimal Hours
A duration like 8 hours 30 minutes can be used as decimal hours for spreadsheets.
Result: 8 h 30 min equals 8.5 decimal hours.
Sum Time Durations
Multiple time durations can be added to a total duration.
Result: 1 h 45 min plus 2 h 30 min plus 50 min equals 5 h 5 min.
Duration Across Midnight
If the end time is before the start time, the hours calculator calculates until the next day.
Result: The time span across midnight yields 7 h 45 min and 7.75 decimal hours.
Shift a time
A time is moved forward or back by a duration, crossing midnight if needed.
Result: 09:15 plus 7 h 30 min gives 16:45 on the same calendar day.
Notes
Common mistakes
Decimal hours read as hours:minutes
7.5 hours are interpreted as 7 hours 50 minutes because the decimal part is read like minutes.
0.5 hours are 30 minutes (0.5 x 60), not 50 minutes. The calculator shows both formats side by side to avoid confusion.
End time before start time seen as error
An end time of 06:00 with a start time of 22:00 is considered an invalid input or interpreted as a negative duration.
The calculator automatically recognizes the time transition across midnight. 22:00 to 06:00 yields 8 hours, not minus 16 hours.
Rounding errors in decimal hours
20 minutes are noted as 0.2 hours instead of 0.3333 hours. This leads to systematic errors in payroll.
20 minutes / 60 = 0.3333... decimal hours. The calculator displays up to four decimal places; when converting back from decimal hours it rounds to whole minutes.
Minute sum not carried over to hours
When adding times, minutes over 60 are not converted to full hours: 2:45 + 1:30 is noted as 3:75.
75 minutes are 1 hour and 15 minutes. The correct sum is 4:15. The calculator handles the carry-over automatically.
FAQ
Frequently asked questions
How does the hours calculator compute the duration?
It converts start and end time to minutes since the start of the day and forms the difference. If end time is before start time, it is calculated until the next day.
What happens when the end time is before the start time?
Then the calculator treats the end time as the next day. From 22:30 to 06:15 yields for example 7 hours 45 minutes.
What does decimal hours mean?
Decimal hours express minutes as a decimal fraction of an hour. 7 hours 30 minutes equals 7.5 hours.
How do I convert decimal hours to hours and minutes?
Decimal hours are multiplied by 60. 7.5 hours yield 450 minutes, so 7 hours and 30 minutes.
How do I convert hours and minutes to decimal hours?
The hours are converted to minutes, the minutes added and the sum divided by 60. 8 hours 30 minutes yield 8.5 hours.
Can I add multiple times?
Yes. In the sum mode, up to three time durations in hours and minutes can be added.
Is this a working time calculator with breaks?
No. The hours calculator remains a general time duration calculator. For breaks, work start, work end and net working time, the working time calculator is more suitable.
How does the calculator round decimal hours and minutes?
When converting decimal hours, the engine rounds the product of decimal hours and 60 to the nearest whole minute. In the opposite direction, it displays the decimal value with up to four decimal places. Contractual or workplace rounding rules are not checked.
Limits
Limitations
The hours calculator does not account for breaks. For working time with break deduction, use the working time calculator.
The duration calculation is limited to a maximum of 24 hours. Multi-day time spans cannot be calculated.
In the sum mode, a maximum of three time durations can be added. For longer lists, a spreadsheet is more suitable.
The calculator works to the minute. Seconds and milliseconds are not considered, so decimal hours are rounded to whole minutes during conversion.
Sources
Sources and references
ISO 8601 – Darstellung von ZeitdauernInternationale Organisation für Normung (ISO)
International standard for the unambiguous representation of Gregorian dates, times and time intervals. It supports the 24-hour representation used here, not any employment-law assessment.
View sourceRetrieved: 07/29/2026 · Verified on: 07/29/2026
DIN 5008 – Schreibweise von UhrzeitenDeutsches Institut für Normung (DIN)
German standard for writing times with colon separation (HH:MM) and for specifying time durations in hours and minutes.
View sourceRetrieved: 07/29/2026 · Verified on: 07/29/2026
SI Brochure – Zeiteinheiten Minute und StundeInternationales Büro für Maß und Gewicht (BIPM)
The SI Brochure lists the minute and hour as time units accepted for use with the SI: 1 minute = 60 seconds and 1 hour = 60 minutes.
View sourceRetrieved: 07/29/2026 · Verified on: 07/29/2026
The age calculator uses date differences for age, birthdays and reference dates.
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