Free Monitor Refresh Rate Test
Estimate visible-tab animation cadence in Hz with median frame intervals and slow-frame counts. Compare local browser timing without claiming exact panel specifications.
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How to use the monitor refresh rate test
Estimate visible-tab animation cadence in Hz with median frame intervals and slow-frame counts. Compare local browser timing without claiming exact panel specifications.
- Choose a five, eight or fifteen-second sampling duration.
- Select Measure refresh rate and keep the tab visible throughout the sample.
- Allow one second of warm-up before the remaining intervals are measured.
- Review the estimated cadence, median interval and slow frames; stop or repeat under similar conditions.
When a refresh rate check is useful
You bought a 144 Hz or 165 Hz monitor, but games still feel like 60 Hz. A quick browser test tells you what rate your screen and browser are actually delivering right now. It is often the first clue that a cable, port, or display setting is holding the panel back.
Laptop owners use it after switching between battery and plugged-in power, since many systems lower the rate to save energy. People with more than one monitor use it to confirm which screen runs at which rate. It is also handy after a driver update, when settings sometimes reset to a default.
Streamers and competitive players also run it before a match or broadcast, simply to confirm nothing changed since the last session. It takes seconds, needs no download, and runs entirely in the browser tab you already have open.
A worked example
Choose the 8 second test and keep the tab visible. After a 1 second warm-up, the browser records the time between animation frames. Suppose the median interval comes out at 6.94 ms. The estimate is 1000 divided by 6.94, which is about 144 Hz.
On a standard screen the median would sit near 16.67 ms, and 1000 divided by 16.67 gives about 60 Hz. Alongside the estimate you see the average interval, the number of samples collected, and a count of slow frames. A slow frame is any interval longer than 1.5 times the median, so with a 6.94 ms median, anything above about 10.4 ms counts as slow.
How the measurement works
Browsers call requestAnimationFrame once per screen refresh when they can keep up. The test logs each interval between those calls and keeps only values between 0 and 1000 ms. It needs at least 20 samples before it reports a result, and you can run it for 5, 8, or 15 seconds.
The median is used instead of the average because one long pause would drag an average down. The median ignores those outliers and reflects the typical frame time. The average and slow frame count are still shown so you can see how steady the browser was during the run.
If you hide the tab or switch away, the browser pauses animation frames to save power. The test aborts in that case rather than report a misleading number.
Common mistakes to avoid
Do not run the test with heavy apps, video exports, or many busy tabs in the background. A busy system can miss frames and lower the reading. Close what you can and use the 15 second option for a steadier result.
Remember the result reflects the screen the browser window is on. If you drag the window to another monitor, run the test again. And if the number is lower than expected, check the display refresh setting in your operating system and the cable type before assuming the monitor is faulty.
Useful tips and limitations
- Browser load, power saving and variable refresh can change the estimate.
- Use the operating-system display settings to verify the panel mode rather than treating this estimate as a specification.
- Run the test twice, once on battery and once plugged in, to see whether a laptop power mode changes the rate.
- A high slow frame count with a correct Hz reading usually points to background load rather than a display setting.
Common questions
Does the refresh-rate estimate always match the monitor specification?
No. It measures animation scheduling in the visible browser tab, which can be throttled or limited independently of the panel.
What happens if the refresh-rate sampling tab is hidden?
The test interrupts sampling and asks you to retry in a visible tab instead of presenting background-throttled timing as a valid result.
How is the Hz number calculated?
It is 1000 divided by the median interval between animation frames in milliseconds, so a 16.67 ms median gives about 60 Hz.
What counts as a slow frame?
Any frame interval longer than 1.5 times the median interval measured during that run.
Which test length should I pick?
The 5 second test is quick, while the 15 second test collects more samples and is less affected by brief hiccups.
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