Refresh rate test
The refresh rate your browser is actually rendering at, taken from the median of several hundred frame times rather than an average.
Observed refresh rate. Press Measure to start.
- Frame time
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- Jitter
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- Dropped frames
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- Samples
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Each bar is one frame. Green is within 20 per cent of the median, amber within 50 per cent, red beyond that.
Visual check
Three blocks moving at the same real-world speed on every display, because position comes from elapsed time rather than a per-frame step. Smooth here means good frame pacing.
How to run this test
- Close anything heavy in the background. A video call or a game in another window will drag the reading down, because the browser is sharing the same frame budget.
- Press Measure and leave the tab in the foreground. The test aborts if the tab is hidden, because a background tab is throttled and the numbers would be meaningless.
- Wait for the run to finish. Five seconds is enough on a steady display; use thirty if you are chasing an intermittent stutter.
- Read the headline figure, then check jitter and dropped frames underneath. A clean 144 Hz with forty dropped frames is not the same result as a clean 144 Hz with none.
- Watch the three moving blocks as a sanity check. They travel at the same real-world speed regardless of refresh rate, so uneven motion there is frame pacing, not speed.
What a problem looks like
- It reads 60 Hz on a high refresh rate display
- Almost always a setting rather than a fault. Check the refresh rate in your operating system display settings, check that your laptop is not in a battery-saving mode, and check that hardware acceleration is enabled in your browser. A cable or port that cannot carry the full rate at your resolution is the next thing to check.
- The number will not sit still
- Expected on a variable refresh rate display. FreeSync and G-Sync deliberately vary the refresh rate to match what is being drawn, so a fluctuating figure is the system working as designed rather than a problem.
- High jitter with a plausible rate
- Frames are arriving at uneven intervals even though the average is right. This is what stutter feels like. Background processes, a browser extension doing work on every frame, or a GPU that is thermally throttling are the usual causes.
- A large dropped-frame count
- Frames taking more than one and a half times the median interval. A handful over five seconds is normal. Dozens means something is interrupting the render loop regularly, which is worth investigating before blaming the display.
- A rate that matches nothing standard
- If the measured figure does not snap to a known mode, the browser is likely not getting a clean vertical sync signal. Disabled hardware acceleration and remote desktop sessions both produce this.
What to do next
If something looks wrong, check it again in a normally lit room and from straight on, then check whether it appears on a second device. If it only happens on this screen and you are still inside the return window, that is the time to contact the retailer.
Questions people actually ask
Is this measuring my monitor or my browser?
Your browser, which normally amounts to the same thing. The page counts how often the browser paints a frame, and browsers are synchronised to the display refresh. Where the two diverge, power saving, disabled hardware acceleration, a throttled tab, the browser figure is the lower one, and the page tells you what to check.
Why use a median instead of an average?
Because a single pause destroys an average. One 200 millisecond stall in a five second run at 144 Hz drags the mean down far enough to report a completely wrong mode. The median ignores a minority of outliers, so the headline figure stays correct and the stalls get counted separately as dropped frames.
Can you tell me the maximum refresh rate my monitor supports?
No. A browser can only observe the rate it is currently being given. Your panel maximum is in its specification sheet and in your operating system display settings, neither of which is available to a web page.
Why does my laptop report 60 Hz on battery?
Many laptops drop the panel to 60 Hz on battery power to save energy, and some do it silently. Plug in, or change the power mode, and run the test again. This is the single most common explanation for an unexpectedly low reading.
What counts as a good jitter figure?
On a steady 60 Hz display, under about half a millisecond is very clean and anything under one millisecond is fine. On a variable refresh rate display the figure will be much larger by design, so read it alongside the note about whether the rate looked variable.