Hz Test — What Is My Screen's Hertz?

Reading your Hz result

The big number is the measured rate, not a rounded label. Panels are built to tolerances, so a monitor sold as 144Hz commonly measures 143.86 Hz, and a 60Hz panel derived from TV timing measures 59.94 Hz. Those small fractions are normal and harmless. What is not normal is a big gap: a gaming monitor measuring 60.00 when it should measure 144 means something in the chain — operating system setting, cable, port, dock or power mode — is holding it back, and the panel has been running at the lower rate the whole time.

Below the number you will find the supporting statistics. Frame time is the same measurement expressed in milliseconds. Jitter tells you how steady the rhythm is: a healthy display repeats its frame time within a few tenths of a millisecond, while a jittery one alternates long and short frames, which the eye reads as roughness even when the average rate is correct. Dropped frames are refreshes where no new frame arrived at all. Together they separate three very different situations that a single rounded number would blur: running at the wrong rate, running at the right rate unevenly, and running perfectly.

Why does my high-refresh monitor show 60?

This is the single most common problem this test uncovers: someone buys a 144Hz monitor, plugs it in, and Windows quietly keeps it at 60Hz. Work through the checklist in order. First, open your operating system display settings and set the refresh rate to the highest value listed — on Windows that is Settings, System, Display, Advanced display; on macOS it is System Settings, Displays, Refresh Rate. Second, check the cable and port: many older HDMI cables and some laptop docks cap out at 60Hz at higher resolutions, while DisplayPort or a certified high-speed HDMI cable carries the full rate. Third, plug laptops into power and turn off battery-saver mode, which commonly caps rendering at 60 or even 30 frames per second. Fourth, disconnect a second, slower monitor temporarily — mixed refresh rates can drag the compositor to the lowest common rate. Fifth, make sure hardware acceleration is enabled in your browser settings, and test in a second browser to rule out an extension. Run the test again after each change; the detected rate should jump the moment the real bottleneck is gone.

Hz and FPS: the short version

Hertz is the screen's capacity; FPS is the software's output. A 240Hz monitor fed by a game running at 70 FPS shows 70 smooth-ish frames spread across 240 refreshes. A 60Hz monitor fed 300 FPS still only shows 60 pictures a second. For the output side of the picture, run the FPS test; for uneven delivery at the right rate, see the stutter test. The full explanation lives in our guide to FPS vs refresh rate.

How to run the Hz test

1. Just open the page — measurement starts immediately and the number settles within a few seconds.
2. Keep the tab visible; background tabs are throttled and would read near 1 Hz.
3. Compare the measured value with your display's rated rate. If it matches within a hertz or two, you are done.
4. If it does not match, use the checklist above, change one thing at a time, and watch the number respond.