Click Start to begin; results render below as the diagnostic runs. The live Hz readout tracks the current rate, and the Adaptive refresh tracking panel underneath records the session minimum and maximum, lists each stable rate observed, and reports when the display switches rates - useful on ProMotion phones, MacBook Pro screens, and variable-refresh gaming monitors.
Ready. Click Start measuring to sample requestAnimationFrame timing in this tab. Nothing is uploaded.
frames: 0 | avgDelta: -- ms | samples: 0
min: -- Hz | max: -- Hz
stable rates observed: --
Monitor Refresh Rate Test (Hz)
Estimate your display refresh rate from requestAnimationFrame timing in the browser.
Click Start measuring, keep this tab visible, and read the live Hz estimate from frame deltas.
Stop or Reset anytime; nothing is uploaded and no account is required. No camera or microphone permission is requested.
Adaptive refresh rate (ProMotion, LTPO, variable refresh)
Many modern screens do not run at one fixed speed. Recent iPhone Pro and iPad Pro models and 14-inch and 16-inch MacBook Pro displays use ProMotion panels that shift between low rates and 120 Hz depending on what is on screen, and gaming monitors with variable refresh can move across a wide range such as 48 to 165 Hz. The Adaptive refresh tracking panel on this page is built for exactly that case: while you measure, it records the minimum and maximum rate seen in the session, lists each stable rate the browser held for a moment (for example both ~60 Hz and ~120 Hz), and draws a small chart showing how much time was spent near each common rate. When two clearly different stable rates appear, the panel reports that rate switching was observed - the behavior signature of an adaptive display. A small moving dot animates during measurement so panels that lower their rate on still content have a reason to speed up.
Two honest limits to keep in mind. The browser only exposes frame timing, so this test observes how the display behaves right now; it cannot read the panel's full supported range from hardware. And some devices cap web animation below the panel maximum: an iPhone in Low Power Mode, or Safari before its full-rate setting is enabled, may report ~60 Hz even on a 120 Hz screen. If the number looks low, plug in, disable power saving, and try again.
Frequently Asked Questions
What does Monitor Refresh Rate Test (Hz) measure?
It samples requestAnimationFrame timestamps and estimates Hz from the median frame delta. Results stay in the tab.
Do I need camera or microphone access?
No. This tool uses animation-frame timing only - no getUserMedia.
Why does the reading drop when I switch tabs?
Background tabs throttle requestAnimationFrame. Keep this tab in the foreground while measuring.
Is timing data uploaded?
No. Samples stay in the page session. Reset clears them; closing the tab drops them.
Can it detect an adaptive refresh display like ProMotion or a VRR gaming monitor?
Yes, by behavior. The Adaptive refresh tracking panel records the session minimum and maximum rate, lists each stable rate observed, and reports rate switching when two clearly different stable rates appear - the signature of ProMotion, LTPO, or variable-refresh panels. It observes what the display does in this browser; it cannot read the panel's full supported range from hardware.
Why does my 120 Hz iPhone or MacBook show only ~60 Hz?
Some devices cap web animation below the panel maximum. Common causes: Low Power Mode on iPhone, Safari without its full frame-rate setting enabled, battery-saver profiles on laptops, or an external monitor cable or OS setting fixed at 60 Hz. Remove the cap and measure again.
What do the stable-rate list and the chart mean?
A stable rate is a stretch of frames the browser held near one speed, such as ~60 Hz or ~120 Hz. The chart shows how much of the session was spent near each common rate, so an adaptive panel typically shows two or more bars while a fixed panel shows one.