Unit Converter
Convert between common units of length, mass, and area.
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Time Duration Calculator
Calculate elapsed time, including durations crossing midnight.
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How to use time duration calculator
- Enter Start time and End time, including seconds when needed.
- Enable End is on the next day for an interval crossing into the following day.
- Select Convert / calculate and compare the hours/minutes/seconds with Total minutes.
Work through an example
Measure a clock interval across midnight, use the next-day setting, and distinguish time-of-day arithmetic from dated elapsed time.
Calculate an overnight duration without guessing the date →Formats, privacy, and practical limits
This tool processes the values you enter in your browser. No account or upload to ERITHRA is required.
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Frequently asked questions
Does next day account for daylight-saving transitions?
No. It adds exactly 86400 seconds. Dates and time zones are outside this time-of-day calculation.
Why is an earlier end time rejected?
With next day disabled, it would create a negative interval. Enable the checkbox only when the end really falls on the following day.