Refresh Rate Test: Verify Your Real Hz In-Browser (60 / 120 / 144 / 165+)
A 144 Hz monitor running at 60 Hz is the most common silent misconfiguration in PC gaming — you lose more than half the smoothness you paid for and nothing ever warns you. This refresh rate test measures your display's true refresh rate in the browser, synchronized to the hardware vsync clock, and shows frame-time jitter that raw FPS counters miss.
What refresh rate means — and what it does not
Refresh rate is how many times per second the display redraws the image, measured in hertz (Hz). A 144 Hz panel redraws every 6.9 ms; a 60 Hz panel every 16.7 ms. Higher refresh rates visibly improve motion clarity, cursor fluidity, and perceived input latency — the mouse pointer alone is dramatically smoother at 120 Hz+.
Refresh rate is a property of the panel and the display link; frame rate is a property of your content. A 300 FPS game on a 60 Hz monitor still shows at most 60 unique frames per second. Conversely, desktop smoothness depends only on refresh rate, which is why this test measures the display signal, not game performance.
Note that advertised "motion rate" or "TRUMOTION 240" figures on TVs are marketing numbers that combine backlight scanning with interpolation, not true panel refresh. A browser test like this one measures what the panel actually accepts.
How this test measures your real Hz
The test locks an animation loop to the browser's requestAnimationFrame clock, which fires in sync with the display's vertical blanking interval — the hardware vsync. By timestamping hundreds of consecutive frames and computing the median interval, the tool reads the actual display refresh signal rather than trusting the OS-reported mode.
The millisecond frame-time graph plots each interval as it happens. A healthy display shows a flat line at 16.7 ms (60 Hz), 8.3 ms (120 Hz), 6.9 ms (144 Hz), or 6.1 ms (165 Hz). Dips and spikes indicate dropped or duplicated frames — micro-stutter you feel in games but cannot see in an FPS number.
Because the measurement rides on vsync, close other tabs and animations before testing for a clean read, and run it fullscreen for the most stable intervals. On multi-monitor setups, drag the browser window onto each display in turn to verify each link.
Reading the result: common outcomes
Reads 60 Hz on a high-refresh monitor: the display link is running at 60 Hz. On Windows, check Settings → System → Display → Advanced display settings → refresh rate (this is unset surprisingly often). On macOS, check System Settings → Displays — ProMotion displays default to adaptive and may report low until content demands more.
Reads the expected Hz but games feel choppy: the panel is fine; the game is not hitting frame rate. That is a GPU/settings problem, not a display one — look at in-game FPS, not the display.
Reads an odd intermediate value (e.g., 100 Hz on a 144 Hz panel): you are likely on a bandwidth-limited link. HDMI versions and older DisplayPort modes cap out below native refresh at high resolutions — see below.
Why high-refresh monitors get stuck at 60 Hz
Cable and port bandwidth is the number-one cause. A 4K 144 Hz signal needs roughly HDMI 2.1 or DisplayPort 1.4 with DSC; plugging into an older cable, a passive adapter, or the wrong GPU port silently drops the link to 60 Hz or 4K30. Use a certified cable and plug directly into the GPU, not a dock or motherboard video.
The second cause is the OS setting itself — both Windows and macOS default new displays to 60 Hz and wait for you to opt up. The third is driver-level: on Windows, "Display port 1.2" mode limits 1440p to 60 Hz on some panels; in NVIDIA/AMD control panels, create a custom resolution at native refresh if the standard mode is missing.
Once the test confirms your full refresh rate, keep the motion-clarity demo running: the sliding box at multiple speeds makes overdrive artifacts and response-time smear visible, which pairs with the checkerboard modes in our burn-in toolset and completes a full panel evaluation alongside the resolution check.
Frequently Asked Questions
What is a refresh rate test?+
A test that measures how many times per second your display actually redraws. This page uses the browser's vsync-synchronized animation clock to read the real refresh signal — 60, 100, 120, 144, 165 Hz or higher — and plots frame-time stability alongside it.
How do I check my monitor's Hz in the browser?+
Open this page, click to start the test, and read the measured value after a few seconds of stable sampling. The number shown is the median interval of hundreds of hardware-synchronized frames — the display's true operating refresh rate.
Why does my 144 Hz monitor only show 60 Hz?+
Most often the OS refresh-rate setting is still on its 60 Hz default, or the cable/port cannot carry the bandwidth. Set the refresh rate in your display settings, use a certified HDMI 2.1 / DisplayPort 1.4 cable plugged directly into the GPU, and re-run the test.
Can a browser really measure refresh rate accurately?+
Yes. The requestAnimationFrame clock fires once per display refresh, locked to the vsync signal. Averaging hundreds of frame intervals gives the actual panel refresh with sub-millisecond precision — the same mechanism professional tools use in the browser.
Does refresh rate matter outside gaming?+
Very much. Scrolling, window dragging, and cursor movement are visibly smoother at 120 Hz+, and latency drops. For office and browsing use, going from 60 to 120 Hz is one of the most noticeable upgrades you can make to a computer.
What is the difference between Hz and FPS?+
Hz is how often the display redraws; FPS is how many frames your content produces. Effective smoothness is capped by the lower of the two. This page measures Hz — the display side — which is why desktop motion smoothness shows here even with no game running.