Monitor Hz test
Find out in 4 seconds whether your screen is delivering the Hz you paid for.
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HzRefresh rate
The test takes 4 seconds. Keep this tab visible and don't switch windows while it runs — the browser stops counting frames when the tab loses focus.
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How the test works
Buying a 144 Hz monitor does not mean you are playing at 144 Hz. Windows often sets the display to 60 Hz by default, and people go months without noticing, blaming the graphics card instead. This test measures how many frames per second the browser can draw and estimates the refresh rate your screen is actually delivering right now.
How the test works
- The browser draws frames in step with the display. The test timestamps every frame for 4 seconds and measures the interval between them.
- The calculation uses the median of the intervals, not the average. An occasional hitch — garbage collection, a heavy tab — creates one long interval that would ruin the average; the median ignores those spikes.
- The result is converted to Hz and compared with market rates (60, 75, 120, 144, 165, 240) to suggest the closest one.
- The test also measures how much the frames varied. A lot of variation points to a variable refresh rate display or an overloaded browser.
How to read the result
- You got close to 60 Hz and your monitor is 144 or 165: it is almost always a setting. In Windows, go to Settings, System, Display, Advanced display settings and pick the highest rate available.
- You got close to the expected value: your display is set up correctly. If the game still feels choppy, the bottleneck is elsewhere — low FPS, stuttering and input lag are different problems.
- You got an odd number, like 143 or 164: that is normal. The browser clock has a margin of error, and a difference of one or two Hz means nothing.
- You got above 240: possible, but confirm in the Windows display panel. Some browsers draw more frames than the screen shows.
Where this test stops
- It measures what the BROWSER can draw, which is not necessarily the physical refresh rate of the monitor. The two numbers match in most cases, but not always.
- A background tab is throttled by the browser. If you switch windows during the measurement, the result comes out wrong and low.
- A laptop in power-saving mode usually lowers the display rate. Plug it in and repeat if the number looks low.
- With two displays at different rates, the result is for the display where the browser window is.
- Variable refresh rate displays (G-Sync, FreeSync) change the rate with the load. The number will fluctuate, and that is expected behavior.
- This test does not measure pixel response time, ghosting or input lag. Those are different things from refresh rate.
Common problems
My monitor is 144 Hz but the test says 60. What do I do?
Open Windows Settings, go to System, Display, Advanced display settings and select the highest rate in the list. If 144 is not there, the cable is usually the problem: old HDMI does not have the bandwidth for 144 Hz at 1080p. Use DisplayPort or HDMI 2.0 or newer.
The result changes every time I measure.
Some variation is normal. Large variation, tens of Hz, points to an active variable refresh rate, an overloaded browser or something heavy running in the background. Close other tabs and programs and measure again.
Does it work on a phone?
It does, and it measures the refresh rate of the phone screen. Many phones lower the rate automatically to save battery, so the number can change between runs without anything being wrong.
The rate is right, but the game still stutters.
Refresh rate and in-game smoothness are separate things. Stuttering with the display set correctly points to low FPS, stutter from DPC latency or background processes eating CPU — none of which show up in this test.
What next?
Did the test find something odd?
If the rate is correct and the game still does not feel smooth, the bottleneck is somewhere else. It is almost always Windows configuration: power plan, process scheduling, drivers or background processes. That is exactly what the UPBOOST optimization tunes, measured before and after in front of you.