Time Math Center
Learn the mathematics of clocks and time. Add and subtract time, find elapsed time, convert hours and minutes, calculate clock-hand angles, practice reading an analog clock, and understand how fractions, decimals and percentages connect to a day.
Elapsed Time Calculator
Find the time between two clock times, including overnight spans.
If the end time is earlier than the start time, the calculator treats it as the following day.
Add or Subtract Time
Start with a clock time, then move forward or backward by hours and minutes.
Clock Hand Angle
Find the smaller angle between the hour and minute hands. The hour hand moves continuously as the minutes pass.
Formula: |30 × hour − 5.5 × minutes|, then use the smaller angle if the result is over 180°.
Interactive Clock Practice
Hours, Minutes & Seconds Converter
Convert a quantity of time into equivalent units.
Decimal Hours ↔ Hours:Minutes
Useful for timesheets, payroll and learning why 1.5 hours means 1 hour 30 minutes—not 1 hour 50 minutes.
Why?
The decimal part is a fraction of 60 minutes. So 0.75 × 60 = 45 minutes.
12-Hour ↔ 24-Hour Time
Fractions & Percent of a Day
A day has 24 hours, 1,440 minutes and 86,400 seconds.
This connects clock math to fractions, ratios, decimals and percentages.
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