Stopwatch lap calculator
Turn a list of recorded lap times into a full breakdown with splits, deltas and the fastest and slowest lap.
Stopwatch lap calculator
Paste a list of lap times captured from a stopwatch, a running watch or a race splits sheet — one per line, in mm:ss.cc or hh:mm:ss.cc — and this tool turns them into a full lap breakdown: order, running total, the change from the previous lap, and which lap was fastest and which was slowest. It's built for runners, swimmers, cyclists and anyone timing repeated intervals who wants more than a raw list of numbers.
Choose how much precision to keep — whole seconds, tenths or hundredths — and pick a time format: mm:ss, hh:mm:ss or plain total seconds. Compare each lap to the one right before it, or switch to comparing every lap against the first to see how pace drifts over a session. Turn on highlighting to mark the fastest lap directly in the list, and switch the output between a readable text report, an aligned table or CSV for a spreadsheet.
Add a short note after a lap time — separated by a dash, comma or colon — to keep labels like "warm-up" or "interval 3" attached to each row. Blank lines and both Windows and Unix line endings are handled automatically, and a line that isn't a recognizable time is reported by its exact position so it's easy to fix. Leave the input empty and the tool simply shows a stopwatch reading zero in the format you picked.
All parsing and calculation happen in your browser — no lap times are ever uploaded anywhere. Copy the report, download it as a .txt file, or send the output back into the input to tweak the options and recalculate.