My Calculator Stack · Time formulas
Time formulas
A short printable sheet for the Time tools — the stopwatch lap-style elapsed-time helpers and the exam countdown identities shown beside those calculators. For calendar math (days, age, date offsets), use the Date Time formula sheet and calculators instead.
Exam Timer
Open tool →
\[ t_{\mathrm{left}} = T - t_{\mathrm{elapsed}} \]
Remaining time is the configured duration minus the time that has actually run (pauses are skipped).
\[ p = t_{\mathrm{left}} / T \]
The progress bar is remaining divided by the original duration: full at start, empty at zero. Reset returns to the configured duration and clears the start time.
Stopwatch
Open tool →
\[ \Delta t = t_{1} - t_{0} \]
Elapsed time is the difference between the current clock reading and the start reading (plus any time already accumulated before a pause).
Keep going
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