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About this tool
Check your monitor's refresh rate in Hz online, with frame-time graph, jitter and dropped-frame counter, plus a motion test for ghosting and frame skips.
This refresh rate test measures how often your browser paints the screen by timing the interval between requestAnimationFrame callbacks, which browsers align to the display's refresh. It keeps the last 240 intervals, takes the median frame time and converts it to hertz, so a single hitch does not skew the result, and snaps the figure to the nearest common rate such as 60, 120, 144 or 240 Hz. Alongside it you get jitter (standard deviation), the 5th–95th percentile range, min and max frame times, and a count of dropped frames longer than 1.5 times the median. A motion test compares objects updated every frame, every 2nd and every 4th frame.
Open Refresh Rate Test on AltFTool — it loads instantly in your browser.
Keep this tab in the foreground on the monitor you want to test; Your refresh rate shows the nearest standard Hz (for example 144 Hz) once about 60 frames have been timed.
Read the Frame time, Jitter, Range (5th–95th percentile), Min / max and Dropped frames tiles, and watch the Frame time (ms) graph for red dots above the dashed 1.5× threshold.
In Motion test pick a speed of 240, 480, 960 or 1440 px/s and compare the Every frame lane with the Every 2nd and Every 4th frame lanes; press Fullscreen for a cleaner view.
After moving the window to another display or changing the Hz setting, press Restart measurement, then Copy result to save the Hz, frame time and dropped-frame figures as text.
Using the median of 240 frame intervals rather than a simple average means background hiccups do not drag the reading down, and the result snaps to the nearest standard rate within 3%.
A live frame-time graph marks every long frame, and jitter, percentile range and a dropped-frame counter show how steady the display pipeline really is.
Three lanes move at your chosen speed, updated at full, half and quarter rate, so you can see what higher refresh buys you and spot ghosting or stutter. Fullscreen is one click.
Background tabs, battery saver and variable refresh rate are explained in place, measurement pauses while the tab is hidden, and the motion test respects reduced-motion settings.
| Refresh rate | Frame time | Common on |
|---|---|---|
| 60 Hz | 16.67 ms | Standard monitors, most laptops and TVs |
| 75 Hz | 13.33 ms | Budget office and entry gaming monitors |
| 90 Hz | 11.11 ms | Phones, VR headsets |
| 120 Hz | 8.33 ms | Phones, tablets, TVs, laptops |
| 144 Hz | 6.94 ms | Mainstream gaming monitors |
| 165 Hz | 6.06 ms | Gaming monitors and laptops |
| 240 Hz | 4.17 ms | Esports monitors |
| 360 Hz | 2.78 ms | High-end esports monitors |
Frame time is 1000 ÷ Hz. A dropped frame shows up as an interval close to twice the normal frame time.
Open this page on the monitor and wait a couple of seconds. The large figure is the refresh rate your browser is actually drawing at, measured from frame timing. To see the configured value, check Windows Settings › System › Display › Advanced display, or macOS System Settings › Displays.
The monitor is probably set to 60 Hz in the operating system, or the cable or port cannot carry the higher rate. HDMI 1.4 and older DisplayPort or adapter cables often limit high resolutions to 60 Hz. Battery saver mode, a browser on the wrong display, or disabled hardware acceleration can also cap it.
On a stable system the median is typically within a fraction of a hertz of the true rate, because browsers schedule animation frames to the display's vertical sync. Accuracy drops when the computer is busy, the tab is in the background, or the browser rounds timestamps for privacy, which shows up as higher jitter.
A dropped frame happens when the browser misses a screen refresh, so one image stays on screen for two or more refresh periods. The tool counts any interval longer than 1.5 times the median as dropped and estimates how many refreshes were missed. A few per minute is normal; constant drops indicate a performance problem.
Jitter is how much the time between frames varies, shown as the standard deviation in milliseconds. At 60 Hz each frame should take about 16.7 ms; at 144 Hz about 6.9 ms. Low jitter means smooth, even motion. High jitter feels like micro-stutter even when the average frame rate looks fine.
Yes, but with variable refresh rate the panel can follow the browser's pace instead of running at its maximum, so the reading may float or sit below the advertised rate. For a fixed reading, compare with the operating system's refresh setting or temporarily turn variable refresh off.
It moves the same object across three lanes updated every frame, every 2nd frame and every 4th frame, so you can compare full, half and quarter refresh rates side by side. Faint trails behind the object suggest slow pixel response or ghosting; bright inverse halos suggest overdrive overshoot.
Yes. Mobile browsers also align animation frames to the display, so a 90 Hz or 120 Hz phone should read accordingly. Many phones lower the rate to save power when nothing is moving or in battery saver, so touch or scroll the screen and keep low-power mode off while testing.
Browsers differ in how they schedule frames and how precisely they report time. Some cap animation at 60 Hz unless a flag or setting is enabled, and privacy features may round timestamps. If one browser reads 60 Hz and another reads 144 Hz on the same display, the monitor is fine and the browser is limiting it.