How this calculator works
The span is first reduced to seconds, which is the common unit behind days, hours, minutes and clock text. Each reported figure is then that same number divided by the length of the requested unit. Nothing is rounded along the way, so the minutes, seconds, hours and days answers all describe exactly the same span.
Formula
Convert mode: seconds = 86400 x days + 3600 x hours + 60 x minutes + seconds. Add mode: seconds = 3600H1 + 60M1 + S1 + 3600H2 + 60M2 + S2. Total minutes = seconds/60, total hours = seconds/3600 and total days = seconds/86400.
Worked example
One day, one hour and 30 minutes is 86400 + 3600 + 1800 = 91800 seconds. That is 1530 minutes, 25.5 hours or 1.0625 days. Adding 1:30 and 0:45 gives 8100 seconds, which is 135 minutes.
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Frequently asked questions
Why divide by 60 rather than use decimal minutes?
Minutes are already the unit being reported. The division converts seconds into minutes, which gives the same number regardless of whether the span was entered in days, hours or clock text.
Can I add more than two durations?
This page adds two. Use the add time calculator for a longer list, then paste its total into one of these fields.
Are days always 24 hours here?
Yes. The page works on fixed-length days with no dates, time zones or daylight-saving changes. A calendar day that gains or loses an hour is a different measurement and needs dated input.