🔁Refresh rate test

✓ Tested & verified Updated: Aug 11, 2026 How the test works

Refresh rate test

Each bar is one frame the browser was given. Even bars mean a steady picture; tall spikes are frames that arrived late.

Frames delivered

0Hz

This is what the browser received, not what the panel is set to. Windows can report 144 Hz while the browser is capped at 60 by HDMI 1.4, a power-saving profile or hardware acceleration being off.

Frame time—
Fastest frame—
Slowest frame—
Late frames—

Measure for

Keep this tab in front and leave the window where it is while it counts — a background tab is throttled and the reading collapses.

Try also

How is refresh rate measured in a browser?

The Devicedial refresh rate test counts the frames your browser is actually given over three seconds and reports the rate in Hz plus the time each frame takes in milliseconds. It asks for an animation frame, records the timestamp the browser hands back, and takes the median gap between them — the median rather than the average, so one long pause for garbage collection cannot drag the whole result down.

That measures delivered frames, not the mode your panel is set to. The two usually agree, and when they do not, the browser is right about what you are seeing: a 144 Hz monitor that delivers 60 frames a second is showing you 60. Frame time is the same fact stated the other way round — 60 Hz is 16.7 ms per frame, 144 Hz is 6.9 ms, and that gap is what a fast display actually buys you.

The measured figure means more next to its frame time, because that is the unit input lag is counted in. Each row is 1000 divided by the rate, and the last column is what the step from 60 Hz is really worth.

Refresh rate	Frame time	Saved against 60 Hz
60 Hz	16.67 ms	—
75 Hz	13.33 ms	3.3 ms
90 Hz	11.11 ms	5.6 ms
120 Hz	8.33 ms	8.3 ms
144 Hz	6.94 ms	9.7 ms
165 Hz	6.06 ms	10.6 ms
240 Hz	4.17 ms	12.5 ms
360 Hz	2.78 ms	13.9 ms

Half of everything a faster panel can give you is already spent by 120 Hz. The whole distance from 144 to 360 Hz is 4.2 ms, which is less than the step from 60 to 90.

The other display numbers are worth having together: screen resolution reports the pixel grid being refreshed, and the polling rate test measures how often your mouse reports into it. For the human end of the same chain, try the reaction time test — it is measured in the same milliseconds.

Frequently asked questions

Why does my monitor stay at 60 Hz when it is a 144 Hz model?

There are four usual causes. Windows keeps 60 Hz after a driver install until you change it under Settings, System, Display, Advanced display; HDMI 1.4 has the bandwidth for 1080p at 120 Hz but not for 1440p or 4K above 60; battery saving and dynamic refresh rate step the panel down when nothing demands more; and a browser with hardware acceleration turned off composites on the CPU and settles near 60.

Why does the browser report a different rate than Windows?

Because the two are reporting different things. Windows shows the mode the panel is set to; this page shows the frames the browser was actually handed over the last three seconds. If the compositor drops frames, or the system is throttling for power, the delivered rate is lower than the mode — and the delivered rate is the one your eyes get.

Which screen does it measure with two monitors?

The one presenting the browser window. Animation frames are driven by the display the window is on, so drag the window to the other monitor and run the test again to read that panel. A window straddling two displays can produce a figure somewhere between the two, so move it fully across before you trust the number.

Why do I get 143 instead of 144?

Because panels rarely run at a round number and the sample is short. A 144 Hz mode is often 143.98 Hz in the timing standard, and a three second window of delivered frames carries a fraction of a frame of noise at each end. Anything within about one percent of the rated figure is the panel behaving exactly as it should.

Does the reading drop on battery?

Usually, and by design. Laptops with a variable refresh panel drop to 60 Hz or lower on battery to save power, and both Windows and macOS ship a battery saver that caps animation on top of that. Plug in, set the power mode to best performance, and run the test again — if the number jumps, nothing is broken.

Is a higher refresh rate always worth it?

The gains shrink fast, and frame time is what shows it. Going from 60 to 120 Hz removes 8.3 ms from every frame; going from 144 to 240 Hz removes 2.8 ms. The first step is visible to almost everyone, the second is a competitive detail — and neither helps if the source cannot render frames that quickly in the first place.

How the test works

The test requests animation frames in a loop with requestAnimationFrame and records the high-resolution timestamp passed to each callback. It then takes the intervals between consecutive timestamps and uses the median interval, not the mean: a browser occasionally delivers a long frame for reasons that have nothing to do with the display, and an average would carry that outlier into the result. Refresh rate is 1000 divided by the median interval in milliseconds; frame time is the median interval itself, reported alongside it.

What this measures is frames delivered to the page, which is a floor rather than a specification. A browser can be capped below the panel’s mode by power saving, by a variable refresh rate policy, by software compositing when hardware acceleration is off, or by being in a background tab, where the callback rate is throttled deliberately. Everything runs locally and nothing is recorded.

Worked example

With frame times from requestAnimationFrame (ms) 6.94, 6.9, 7.0, 6.94, 6.94, 13.9, 6.94, 6.9, this page works out 144 Hz. One frame at 144 Hz is 6.9 ms — and the 13.9 ms gap is two frame times, so that is one frame the browser never drew.

Median frame6.9 ms
One frame at 60 Hz16.7 ms
Slowest frame13.9 ms

Sources:

Hz and milliseconds are the same number

Frame time is refresh rate turned upside down. Divide 1000 by the rate in Hz and you have the milliseconds a single frame stays on screen. Higher is better in Hz and lower is better in milliseconds, which is the single most common mix-up when people compare monitors.

Milliseconds are the honest scale. In Hz the jump from 60 to 144 looks like more than twice the monitor; in milliseconds it is 16.7 down to 6.9, a saving of under ten thousandths of a second. Neither figure is wrong, but only one of them is comparable to a human reaction time.

A display cannot show frames that were never rendered. The refresh rate is the ceiling, not the result: if the game or the browser produces 45 frames a second, a 240 Hz panel repeats them. This page measures what arrives, which is why it is the number worth trusting.