Đang chọn gợi ý…
Chọn ngẫu nhiên một nội dung dành cho bạn.
Mở ngay → ⏱️
👩🏫 Classroom NEW
Online Stopwatch with Lap Times
Online stopwatch accurate to 10ms, lap recording, fullscreen mode, Space/L/R shortcuts. Perfect for classrooms, experiments, and sports. Works offline.
All tools Browser-only
00:00.000
00:00
Shortcuts: Space = Start/Pause · L = Lap · R = Reset
Stopwatch with 10ms precision, lap recording, fully offline. Great for experiments, sports, classroom timing.
When to use an online stopwatch
- Classroom: time student tasks, presentations, group games.
- Experiments: time chemistry/physics reactions — accurate to 10ms.
- Sports / Training: lap times for running, swimming, jump rope.
- Cooking: time boiling, simmering, fermenting.
- Presentations / Interviews: track total time + each section (lap).
Features
- 10ms precision — built on
performance.now(), no drift over time. - Lap times: hit "Lap" to record splits — auto-shows fastest / slowest / average.
- Fullscreen: tap ⛶ for projector or classroom display.
- Keyboard shortcuts: Space = Start/Pause, L = Lap, R = Reset.
- Offline-ready: works without internet. Great on a classroom iPad.
Stopwatch vs Timer
A stopwatch counts up from zero (how much time has passed). A timer counts down from X to zero (how much time remains). Need a countdown? Use the Classroom Timer.
Who this is for
K-12 teachers, tutors, TAs — classroom organization tools: timers, attendance, group makers, grade averages.
FAQ
Is student roster data safe?
Stored in browser localStorage — no server, no account. Incognito or cache clear = lost. Export CSV regularly for backup.
Does it work offline?
Yes. After the first page load, you can disconnect and the tool keeps working — perfect for classrooms with weak WiFi.
