Last updated: March 2026
What Is the Lap Timer?
Over 300,000 athletes search for lap timers monthly, and for good reason. A lap timer is the essential tool for tracking interval performance during training, races, and timed activities. Unlike a basic stopwatch, a lap timer records each segment individually while keeping the total clock running, giving you both the granular detail and the big picture in one view.
This free online lap timer uses performance.now() for sub-millisecond precision and requestAnimationFrame for smooth 60fps display updates. The timer continues tracking accurately even when the browser tab is in the background, so you will never lose time data during a session.
How to Use the Lap Timer
Getting started is simple. Press Start (or hit the spacebar) to begin timing. As you complete each lap or interval, press the Lap button (or hit L) to record that segment. The timer records your lap time, cumulative split time, and calculates the delta comparing each lap to the previous one.
The delta column is where the real insight lives. A green down arrow means you were faster than the previous lap, while a red up arrow means you slowed down. The exact time difference is shown so you can quantify your pacing consistency. The fastest lap in your session is highlighted in green, and the slowest is highlighted in red.
For runners and cyclists, enable Distance Mode to unlock pace calculations. Enter your lap distance (400m for a standard track, for instance) and the timer will show your pace per kilometer for each lap, your average pace across all laps, and projected finish times for 5K, 10K, half marathon, and marathon distances based on your current average.
Key Features
The statistics panel updates in real time as you record laps. You will see your total time, lap count, average lap time, fastest and slowest laps (with lap numbers), and standard deviation. Standard deviation is particularly useful for athletes focused on pacing consistency — a lower number means your laps are more uniform.
When your session is complete, you can export your data as a CSV file for analysis in a spreadsheet, or copy a formatted text summary to your clipboard for sharing with a coach or training log. The fullscreen mode provides a distraction-free display that is easy to read from across a room or track.
Keyboard shortcuts make hands-free operation possible: Space to start and stop, L to record a lap, R to reset. Combined with fullscreen mode, you can operate the timer with minimal screen interaction during intense training.
Frequently Asked Questions
How accurate is this lap timer?
This lap timer uses performance.now() for sub-millisecond precision and requestAnimationFrame for smooth display updates at 60fps. While browser timing cannot match a dedicated hardware chronograph, the accuracy is within 1-2 milliseconds — more than sufficient for athletic training, interval workouts, and process timing.
What is the difference between lap time and split time?
Lap time measures the duration of a single segment — the interval between pressing the Lap button. Split time is the cumulative elapsed time from the very start. For example, if your first lap takes 1:30 and your second takes 1:45, the split times are 1:30 and 3:15, while the lap times are 1:30 and 1:45.
What does the delta column show?
The delta column compares each lap to the previous one. A green down arrow (â–¼) means you were faster than the previous lap, and a red up arrow (â–²) means you were slower. The exact time difference is shown in seconds. This makes it easy to track whether you are speeding up or slowing down across your session.
How does distance mode work?
Distance mode lets you enter the length of each lap (for example 400 meters for a standard track). The timer then calculates your pace per kilometer for each lap, your average pace, and projected finish times for common race distances: 5K, 10K, half marathon, and full marathon. This is based on your average lap pace.
Can I export my lap data?
Yes. You can export your lap data as a CSV file that opens in any spreadsheet application, or copy a formatted text summary to your clipboard. The export includes all lap times, split times, deltas, and pace data if distance mode is enabled.