Common Time Duration Mistakes

Mistake One: Negative Duration

Entering a start of 22:00 and an end of 06:00 and treating the negative result as broken. The duration crosses midnight, so add a full day of 1,440 minutes to get the correct 8 hours.

Mistake Two: The Decimal Hour Ambiguity

Entering 8.30 to mean 8 hours 30 minutes. Read as a decimal it is 8 hours 18 minutes, so billing at that figure understates 12 minutes per entry.

Mistake Three: Expecting Durations Over 24 Hours

Entering a start and an end two days apart and expecting 48 hours. Two clock readings cannot express more than one day, so days must be counted separately.

Mistake Four: Mixing 12 and 24 Hour Times

Entering 9 for the start and 6 for the end of a night shift without considering which is which. Use 24 hour values throughout so morning and evening are never ambiguous.

Mistake Five: Rounding Before Recording

Rounding 4 hours 59 minutes to 5 hours for convenience. That is a one minute error here, but rounding several short entries can accumulate into a materially wrong total.

Mistake Six: Ignoring the End Point

Treating a meeting from 9:00 to 10:00 as one hour while counting the days it touches inclusively as two. A span and a count are different quantities and are calculated differently.