Stopwatch Timer

A multifunctional online timing tool supporting both stopwatch and countdown modes, offering centisecond precision, lap time recording, fullscreen display, and more. Suitable for sports training, exam timing, cooking reminders, and other scenarios.

Features

Dual Timing Modes

• Countdown Mode: Automatically counts down after setting a target time, stops when reaching zero, suitable for exams, speeches, cooking, and other fixed-time scenarios
• Stopwatch Mode: Counts upward from zero, can pause, continue, and reset at any time, suitable for sports training, work timing, and other scenarios

High-Precision Display

Provides 4-digit time unit display:

• Hours (0-99)
• Minutes (0-59)
• Seconds (0-59)
• Centiseconds (0-99, each centisecond = 0.01 second)

Precision reaches 10 milliseconds, meeting professional timing needs.

Lap Time Recording (Stopwatch Mode)

Stopwatch mode supports lap marking to record multiple time points:

• Record each lap time during sports training
• Record time spent on each stage in workflows
• Record key time points during experiments
• Each mark displays number and precise time

Fullscreen Mode

Supports fullscreen display with large font numbers, suitable for distant viewing or projection. The timer can still be operated normally in fullscreen mode.

Usage

Countdown Mode

1. Select "Countdown" mode
2. Click up/down arrows to adjust hour, minute, second, and centisecond values
3. Click the green play button to start countdown
4. During countdown, click the orange pause button to pause
5. Click the red stop button to end and reset
6. Automatically stops when time reaches zero

Quick setup:

• Click unit labels below numbers for quick identification
• Touch operation supported on mobile
• Up arrow increases time, down arrow decreases time

Stopwatch Mode

1. Select "Stopwatch" mode
2. Click the green play button to start timing
3. Click the purple flag button to mark lap time
4. Click the orange pause button to pause timing
5. Click the green play button to continue timing
6. Click the red stop button to end and reset

Lap recording:

• Each mark adds a record to the panel below
• Displays lap number and timestamp
• Records are arranged in chronological order
• All lap records are automatically cleared when reset

Fullscreen Mode

• Click the "Fullscreen" button to enter fullscreen display
• Press ESC or click the browser's exit fullscreen button to exit
• All functions are available in fullscreen mode
• Suitable for large screen display or distant viewing

Button Functions

• Play (Green): Start or continue timing
• Pause (Orange): Pause timing, time stays at current value
• Stop (Red): End timing and reset to zero
• Reset (Blue): Manually reset to zero (only visible when stopped)
• Mark (Purple): Record current time (only visible when stopwatch is running)

Application Scenarios

Sports Training

• Record lap times for running and swimming
• Interval training timing (such as HIIT, Tabata)
• Competition or test timing
• Athlete training data collection

Work and Study

• Pomodoro Technique timing (25 minutes focus time)
• Exam or speech countdown
• Meeting time management
• Task duration statistics

Daily Life

• Cooking timing (boiling eggs, stewing soup, etc.)
• Laundry and drying reminders
• Children's homework time management
• Meditation or breathing exercise timing

Professional Use

• Experiment process timing
• Industrial process monitoring
• Photography long exposure timing
• Competition referee timing

Technical Notes

The timer uses JavaScript setInterval with a 10-millisecond interval to update time, with a theoretical precision of 0.01 seconds (1 centisecond). Actual precision is affected by browser performance and system load, typically with an error within ±20 milliseconds.

Countdown uses a decrementing algorithm, reducing 1 centisecond every 10ms, with seconds, minutes, and hours automatically handled according to carry rules. Stopwatch uses an incrementing algorithm, carrying over to 1 second when reaching 100 centiseconds.

Time data is not preserved after page refresh. It is recommended to save important timing records promptly.

Notes

• Timer may have reduced precision in background tabs due to browser power-saving mechanisms
• System sleep or lock will pause timing, continuing after resumption
• Fullscreen mode may be limited by browser security policies and require manual user trigger
• Long-duration timing (over 24 hours) is recommended to use professional tools
• Centisecond precision is suitable for general scenarios; professional events should use hardware timers
• Countdown does not emit sound reminders when reaching zero (pay attention to screen changes)
• Lap record quantity has no upper limit, but too many records may affect page performance