Refresh Rate Test
Measures the effective rate your display is presenting right now, with frame time, pacing jitter and a confidence figure. Runs 100% in your browser.
All measurement happens on your device. Nothing is uploaded and there is no sign-up or account.
Controls
Your reading
The three usual causes, in order of likelihood:
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The OS defaults to 60 Hz
Windows: Settings → System → Display → Advanced display → select the higher refresh rate; then confirm it sticks in your GPU's driver control panel.
Other operating systems
macOS: System Settings → Displays → Refresh Rate — pick the higher rate.
ChromeOS: Settings → Display — select the higher refresh rate (a driver update may be required).
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The cable or port can't carry the rate
Port capability depends on the standard version: HDMI 2.0 tops out at roughly 144 Hz at 1080p and 120 Hz at 4K. For 144–240 Hz, or 360 Hz, use HDMI 2.1 or DisplayPort. Try the other port, use a certified cable, and re-test.
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Browser hardware acceleration is off
Check that hardware acceleration is enabled: Chrome/Edge — Settings → System → use hardware acceleration when available; Firefox — Settings → Performance → layer acceleration. Then re-test.
Device context
- Screen resolution —
- Pixel ratio —
- Color depth —
How to Use Refresh Rate Test
How to use
- Select your display's rated refresh rate (the maximum Hz it supports — printed on the monitor box or in its specs).
- Click Start test. Close other tabs and go full-screen for the most accurate reading; the test measures for 12 seconds.
- Watch the live readout: the big number is the snapped Hz, the others are frame time, jitter, confidence and elapsed runtime.
- When the test finishes, read the verdict. If it is below your rated rate, follow the fix steps for your operating system.
What the numbers mean
- Effective Hz — how many times per second your display is actually presenting frames right now (the browser's presentation rate on your screen), snapped to the nearest real panel rate.
- Frame time — the median milliseconds between two frames (1000 ÷ Hz: ≈8.3 ms at 120 Hz, ≈6.9 ms at 144 Hz).
- Jitter (CV) — how evenly frames arrive, as the coefficient of variation of frame intervals. Low is under 5%, Moderate is 5–15%, High is above 15%. Uneven pacing is a different problem from a low rate.
- Confidence — the share of measured frame intervals that fall within ±10% of the median. The closer to 100%, the steadier the reading.
Tips
- Go full-screen and close heavy tabs — stalls in other tabs make the reading noisier.
- If your system runs variable refresh (G-Sync/FreeSync), the banner will offer both readings; disable adaptive sync if you want a single steady number.
- The test measures the display the browser is presenting on — on a healthy, GPU-accelerated system that equals your panel's rate.
Use Cases
Real situations where Refresh Rate Test saves time:
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Verify a new high-refresh monitor
Just unboxed a 144 or 240 Hz monitor? Run the test and confirm in under 30 seconds that the panel is actually rendering above the 60 Hz default.
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Diagnose a 'stuck at 60 Hz' monitor
Select your rated Hz, watch the test measure a lower rate, and follow the three-cause fix guide — display settings, cable/port, or browser hardware acceleration.
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Judge frame pacing before buying hardware
See frame time and jitter together to tell whether your stutter is a low-rate problem or an uneven-pacing problem before you upgrade anything.
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Confirm a fix worked
Changed the cable or enabled 144 Hz in display settings? Re-run the test in one click to confirm the measured rate went up.
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Check a laptop, tablet or phone display
Verify that high-refresh mode is actually enabled on a laptop, tablet or phone by measuring the effective rate directly on the device.
Frequently Asked Questions
- How do I check my monitor's refresh rate online?
- This page measures the effective frame rate of your display right now by timing the browser's animation frames (requestAnimationFrame against a high-resolution clock). It reports the Hz snapped to a real panel rate, the frame time in milliseconds and a confidence figure. No install and no sign-up — all measurement happens on your device.
- My monitor is stuck at 60 Hz. How do I fix it?
- The three usual causes are: (1) the OS defaults to 60 Hz — enable the higher rate in your display settings; (2) the cable or port can't carry the rate (e.g. an old HDMI for 240 Hz) — use the right cable/port; (3) browser hardware acceleration is off — turn it on and re-test. When this tool measures below your rated Hz, it lists the steps for your OS.
- How do I know if my monitor is actually running at 144 Hz?
- Display settings show the requested rate, not the real one. This test measures what actually happens: if the reading snaps to 144 (raw ≈143.6–144 Hz) with a high confidence figure, it is running. If it snaps to 60, follow the fix guide — usually a display setting, a cable or a port.
- What is frame time and why does it fluctuate?
- Frame time is the milliseconds between frames (1000 ÷ Hz: ≈8.3 ms at 120 Hz, ≈6.9 ms at 144 Hz). It fluctuates because of load spikes, thermal throttling and uneven vsync scheduling. This test reports the median frame time and a jitter metric (coefficient of variation) so you can see how even the pacing is.
- What's the difference between refresh rate and FPS, and why is my FPS lower than my refresh rate?
- Refresh rate is how many times per second the panel redraws (Hz); FPS is how many frames per second your apps or the browser actually produce. When FPS is lower than the refresh rate, the panel re-shows frames and you get a lower effective rate — which is exactly what this test measures: the effective presentation rate of your display in the browser.