Free web app
Free Online Stopwatch with Lap Timer
A lap stopwatch, countdown timer, and interval workout timer that run entirely in your browser. Nothing to install, no account, and no ads — press Start and it works. Lap times are recorded to the millisecond and can be copied out as text when you are done.
00:00:00.00
SPACE start / pause · L lap · R reset
What's here
Four timers in one page
- Stopwatch
- Counts up with unlimited laps. Tap the time while it runs to record a lap, and export the full list as text.
- Countdown timer
- Counts down from a preset or a time you enter, with a spoken final countdown and an optional repeat for back-to-back rounds.
- Interval workout timer
- Alternates work and rest for a set number of rounds and announces every change out loud, so the phone can stay in your pocket. Ready to go as a tabata timer, a boxing round timer, a emom timer, or a hiit timer.
- Reaction time test
- Measures your reflexes in milliseconds, plus an aim trainer, a sequence-memory game, and a Stroop test.
Getting started
How to use the stopwatch
- Press Start, or hit the Space bar on a keyboard.
- Tap the running time — or press L — to record a lap split.
- Press Stop to pause, and Reset (R) to clear the laps and start again.
Questions
Frequently asked questions
- Is the online stopwatch free?
- Yes. Every timer on 1SecondLap is free with no ads, no signup, and no download. It runs in your browser and keeps working offline once loaded.
- Does the timer keep running if my screen turns off?
- The stopwatch holds a wake lock while it runs, so the screen stays on. Browsers throttle background tabs, so timing is read from the system clock rather than a counter — switching tabs will not lose time.
- What is the difference between the timer and the interval timer?
- The countdown timer counts down once from a time you pick, optionally repeating. The interval timer alternates work and rest periods for a set number of rounds, announcing each change out loud — the format used for Tabata, HIIT, EMOM, and boxing rounds.
- Can I use it for Tabata or boxing rounds?
- Yes. Workout mode has built-in Tabata (8 × 20s / 10s), HIIT, EMOM, and boxing (3 × 3min / 1min) templates, and you can save your own combination of rounds, work, and rest.
- Do my lap times and workouts get uploaded anywhere?
- No. There is no account and no server. Laps, workouts, and results are stored only in your own browser, and clearing your browser data removes them.
- Does it work on a phone?
- Yes. It is designed for phones first and can be installed to your home screen as an app. On desktop, Space starts and pauses, L records a lap, and R resets.
Training outdoors or in a gym? The 1SecondLap iOS app is coming soon, adding GPS run tracking, Bluetooth gym-machine support, heart-rate zones, and Apple Watch.