Refresh Rate Test

How to check your refresh rate

1. Close other heavy tabs and apps, and plug in the charger if you are on a laptop.
2. Press Measure refresh rate and keep the tab visible for about two seconds. Don’t scroll or move the window during the measurement.
3. Read Refresh rate for the measured value and Closest standard rate for the nearest common rate such as 60, 120, 144 or 165 Hz.
4. Check Jitter (std. dev.) and Late or skipped frames to see how steady the frame timing was. The chart shows every frame; red bars are frames that took too long.
5. Press Start moving object to watch a striped block cross the screen at the selected Speed, and compare motion at different settings.

If the result looks wrong, measure again. The first run after opening a page is sometimes disturbed by the page still loading.

How the measurement works

Browsers call requestAnimationFrame once per screen refresh, just before drawing the next frame. This tool records the timestamp of every frame for two seconds, after a short warm-up, and computes the time between consecutive frames. On a 60 Hz display that is about 16.67 ms; at 144 Hz it is 6.94 ms.

The rate is calculated as:

Refresh rate = 1000 ÷ average frame time (ms)

The average only uses frame times within 25 % of the median, so a single skipped refresh doesn’t drag the result down. Some browsers round timestamps to whole milliseconds for privacy, so single frames look uneven, but the average over a few hundred frames stays accurate. Jitter (std. dev.) is the standard deviation of all frame times: a steady system shows well under a millisecond. Late or skipped frames counts frames that lasted more than 1.5 times the median, which means at least one refresh was missed.

Why you might see a lower rate than expected

• The display mode: a 144 Hz monitor often runs at 60 Hz until you select the higher rate in Windows display settings, macOS Displays or the monitor’s own menu.
• The cable or port: older HDMI versions and some adapters can’t carry high refresh rates at high resolutions. Use DisplayPort or a recent HDMI cable.
• Variable refresh rate and battery saving: G-Sync, FreeSync, Apple ProMotion and adaptive sync on phones can lower the rate when content is static or the battery is low. Laptops often drop to 60 Hz on battery, and phones in power-saving mode do the same. The result is the rate this tab receives right now, not always the panel’s maximum.
• Multiple monitors: some systems run every screen at the rate of the slowest one. Move the browser window to the screen you want to test.
• Browser limits: a few browsers cap animations at 60 fps unless hardware acceleration is on.

Using the moving object

The Motion clarity check moves a striped block at a constant speed. Pixels per frame shows how far it jumps each refresh: at 960 px/s and 60 Hz that is 16 pixels, at 144 Hz under 7. Smaller jumps look smoother and sharper to the eye. If the block stutters regularly, frames are being dropped. Blur trailing behind it comes from the panel’s response time and from how your eye tracks motion on a sample-and-hold display.