Time · Formula sheet

Elapsed Time & Lap Splits

Core stopwatch identities: elapsed difference, paused totals, and lap splits at a glance.

Name Formula
Elapsed time Δt = t₁ − t₀

Difference between stop and start clock readings.

Paused total total = Σ (t_end_i − t_start_i)

Sum only running intervals; ignore time while paused.

Lap split split_n = total_n − total_{n−1}

Interval between consecutive lap snapshots.

Cumulative lap total_n = Σ_{i=1..n} split_i

Running total equals the sum of all splits so far.

Milliseconds → display mm:ss.cc = floor(ms/60000) : floor(ms/1000)%60 : (ms%1000)/10

Common stopwatch formatting from a millisecond counter.

Monotonic clock readings t₀, t₁ from a monotonic clock

Prefer a monotonic clock so wall-clock jumps do not skew Δt.

Related tools

Open a calculator and put these formulas to work.