How accurate is this refresh rate tester?

It estimates browser repaint cadence from requestAnimationFrame timestamps. That cadence generally follows the active display refresh rate, but browser scheduling, power saving, dynamic refresh behavior, and system load can affect the result. System display settings remain the authoritative configuration value.

Why does the test show 60 Hz on a 144 Hz monitor?

The operating system may still be set to 60 Hz, the browser window may be on a 60 Hz display, or the current resolution and connection may not offer 144 Hz. Check Advanced display in Windows or Displays in macOS, then move the whole window onto the intended monitor and restart the test.

Why does the raw Hz number move slightly?

Animation callbacks are scheduled work, so individual intervals vary. The large result uses the median interval and snaps only when it is close to a common refresh rate. The stability score shows how consistently callbacks arrived.

Can this test measure VRR, FreeSync, or G-SYNC range?

No. It can show changes in browser callback cadence, but it cannot certify the panel's variable-refresh range or confirm that a game is using FreeSync or G-SYNC. Use the monitor's status display, graphics-driver tools, and a supported game for that check.

Is monitor Hz the same as game FPS?

No. Refresh rate describes display updates per second. FPS describes frames produced by a game or application. They can influence each other, but they are separate measurements.

Refresh Rate Tester

This refresh rate tester estimates the repaint cadence of the display holding this browser window. Let the five-second sample settle, then compare the result with your system's selected Hz.

Automatic five-second measurement
Runs locally in this browser tab
Hz estimate, frame time, and stability

Live display Hz estimate

Uses a rolling five-second window of browser animation timestamps

Measuring

Estimated refresh rate

--Hz

Raw browser cadence: -- Hz

Keep the window entirely on the display being tested.

Median frame interval: -- ms
Timing stability: --%
Samples: 0
Rolling window: 0.0 s

Recent frame intervalsEven bars indicate steadier timing

Background tabs are throttled. Battery saving, browser load, variable refresh behavior, and a window split across two monitors can also change the estimate.

This is an estimate of browser repaint cadence from requestAnimationFrame timestamps. It cannot read the monitor controller, certify its physical scanout rate, or measure response time and input lag.

How to use the refresh rate tester

Start with the browser window fully contained by one display. This detail matters on a desk where a 60 Hz office monitor sits beside a 144 Hz gaming panel. Keep the tab focused, wait five seconds, and look for an even history chart before treating the large number as useful.

1
Move the window onto the display
Place the whole browser window on the monitor, laptop panel, phone, or tablet being tested. Avoid leaving part of it on another display.
2
Keep this tab visible
Wait until the rolling window reaches five seconds. Browsers slow or pause animation callbacks when a tab is hidden.
3
Read the estimate and frame time
Compare Estimated refresh rate with the value selected in system settings. A 60 Hz interval is about 16.67 ms; 144 Hz is about 6.94 ms.
4
Inspect stability
Even history bars support a steady estimate. Close busy tabs or disable battery saving before repeating a highly variable run.
5
Change one display setting and repeat
Select the intended refresh rate in Windows or macOS, then restart the measurement without moving the browser window.

Display refresh rate test: understanding the result

The browser requests an animation callback before upcoming repaints. MDN notes that this callback frequency generally matches the display refresh rate. This tester measures the interval between those callbacks, uses the median to resist an occasional late frame, and converts that interval to an estimated Hz.

Estimated rate	Frame interval	Common use	What to confirm
60 Hz	16.67 ms	Standard desktop and video	Higher mode was not left disabled
90 Hz	11.11 ms	Phones, tablets, and headsets	Battery mode allows high refresh
120 Hz	8.33 ms	Modern laptops, phones, and TVs	Dynamic mode is behaving as expected
144 Hz	6.94 ms	Gaming monitors	OS, resolution, port, and cable
240 Hz	4.17 ms	High-refresh gaming	Browser and connection support

Monitor refresh rate test for multi-monitor setups

Browsers schedule a window against the display that currently owns it. Drag the window fully onto the monitor under test, wait a moment for the compositor to switch, and press restart. A window straddling two panels can produce confusing timing, especially when one runs at 60 Hz and the other at 144 Hz.

Move

Put every edge of the window on one display.

Settle

Keep the tab visible for five seconds.

Compare

Match the estimate with system settings.

Restart after moving the window. The tool does not receive a monitor model or connection name from the browser.

Screen refresh rate test at 60 Hz, 120 Hz, and 144 Hz

Higher refresh shortens the interval between display updates. Cursor movement and scrolling can look smoother, and a game has more opportunities to present a recent frame. Panel response time still matters. A 144 Hz signal cannot force slow pixels to finish every color transition inside 6.94 ms.

If the chart alternates between regular short intervals and taller bars, close video calls, recording tools, and busy tabs. Retest while plugged in. One laptop on a quiet desk can hold 120 Hz until battery saver flips on, then settle at 60 without an obvious warning.

Testing refresh rate with VRR, DRR, and ProMotion

Variable refresh rate lets a compatible display adjust its updates to content. Windows 11 Dynamic Refresh Rate can change cadence for smoothness and battery life. Apple ProMotion and Adaptive Sync behave similarly at the system level. A browser sample may therefore change when content, power state, or focus changes.

This page estimates the cadence it receives during the test. It cannot map the full VRR range, prove that FreeSync or G-SYNC is active in a game, or reveal the panel's maximum hardware rate while the system deliberately runs lower.

Screen Hz test versus game FPS

Display Hz

How frequently the display updates. This tool estimates browser repaint cadence as a practical signal.

Game FPS

Frames produced or presented by the game. Use the FPS counter guide for native games.

Pixel response

How quickly pixels change. Browser timestamps cannot measure overshoot, ghosting, or gray-to-gray transition time.

How to set monitor refresh rate in Windows and macOS

Windows 11

Open Settings, System, Display, then Advanced display.
Select the intended monitor when several displays are connected.
Choose the rate beside Choose a refresh rate.
Return here, move the window onto that display, and restart.

macOS

Open Apple menu, System Settings, then Displays.
Select the display and open its Refresh Rate menu when available.
Choose a fixed rate, ProMotion, Variable, or Adaptive as supported.
Run the display Hz test again with the tab in front.

High refresh at full resolution requires a port, cable, adapter, GPU, and monitor mode that support the same combination.

Phones may place 90 Hz or 120 Hz under Display, Motion smoothness, or an adaptive refresh setting. Available controls vary by model.

FAQ

How accurate is this refresh rate tester?: It estimates browser repaint cadence from requestAnimationFrame timestamps. That cadence generally follows the active display refresh rate, but browser scheduling, power saving, dynamic refresh behavior, and system load can affect the result. System display settings remain the authoritative configuration value.
Why does the test show 60 Hz on a 144 Hz monitor?: The operating system may still be set to 60 Hz, the browser window may be on a 60 Hz display, or the current resolution and connection may not offer 144 Hz. Check Advanced display in Windows or Displays in macOS, then move the whole window onto the intended monitor and restart the test.
Why does the raw Hz number move slightly?: Animation callbacks are scheduled work, so individual intervals vary. The large result uses the median interval and snaps only when it is close to a common refresh rate. The stability score shows how consistently callbacks arrived.
Can this test measure VRR, FreeSync, or G-SYNC range?: No. It can show changes in browser callback cadence, but it cannot certify the panel's variable-refresh range or confirm that a game is using FreeSync or G-SYNC. Use the monitor's status display, graphics-driver tools, and a supported game for that check.
Is monitor Hz the same as game FPS?: No. Refresh rate describes display updates per second. FPS describes frames produced by a game or application. They can influence each other, but they are separate measurements.

Sources

Links go to official browser docs or primary references when available.