Refresh Rate Test
A 60 Hz screen draws a frame every 16.7 ms, a 144 Hz screen every 6.9 ms. A browser test gives an estimate that power saving, background tabs and other monitors can change.
How to use
- Open the page and keep this tab in front. The test starts by itself and takes about 4 seconds.
- The big number is the estimated refresh rate. The rows show the closest standard rate, the frame time and how stable the reading was.
- Press Measure again to repeat the test, for example after changing the rate in your display settings or moving the window to another monitor.
- If the number is lower than your monitor should give, check the display settings of your system and the notes below before blaming the screen.
How it works
The browser calls requestAnimationFrame once per screen refresh. The tool records the time of each call, throws away the first 30 frames as a warm-up, and takes the gaps between the rest.
Gaps shorter than half or longer than 1.5 times the median gap (a stalled frame, a tab switch) are removed as outliers. Hz = 1000 / mean of the remaining gaps in ms. The spread of those gaps is shown as the stability.
The closest standard rate is picked from 60, 75, 90, 100, 120, 144, 165, 170, 180, 240 and 360 Hz when the estimate is within 3 percent of one of them.
What refresh rate is
Refresh rate is how many times per second the screen draws a new image. At 60 Hz that is every 16.7 ms, at 144 Hz every 6.9 ms. A higher rate makes motion look smoother and cuts the delay between your input and the picture, but only if the system, the cable and the game actually deliver that many frames.
| Rate | Frame time | Where it is common |
|---|---|---|
| 60 Hz | 16.7 ms | Office monitors, most laptops and TVs |
| 75 Hz | 13.3 ms | Budget monitors with a small boost |
| 120 Hz | 8.3 ms | Newer phones, laptops, consoles and TVs |
| 144 Hz | 6.9 ms | Common gaming monitors |
| 240 Hz | 4.2 ms | Esports monitors |
When the result can be wrong
- A background or hidden tab runs the page at a much lower speed. Keep the tab in front and do not switch while it measures.
- Battery saver, low power mode and some laptop power plans make the browser draw fewer frames than the screen can show.
- With several monitors the browser may follow the wrong one, or the slowest one. Put the window fully on the monitor you want to test.
- Safari limits the frame rate in some modes, notably low power mode, and may show 60 Hz on a faster screen.
- Variable refresh rate (G-Sync, FreeSync, adaptive sync) can make the rate change with load, so the reading is not always a clean number.
- Browser flags and settings, such as hardware acceleration being off, can cap the frame rate too.
Setting the right rate
- On Windows open Settings, System, Display, Advanced display and pick the refresh rate. On macOS use System Settings, Displays.
- Use the cable that supports the rate. An old HDMI cable or port can limit a 144 Hz monitor to 60 Hz; DisplayPort usually works.
- After changing the setting, press Measure again.
FAQ
Is my monitor 144Hz?
If the closest standard rate shows 144 Hz and the stability is good, the browser is drawing at 144 frames per second on that screen. That is a strong sign, but a short browser test is still an estimate. Your display settings show the rate the system really uses.
Is the result accurate?
It is an estimate. It is usually within a few percent of the real rate when the tab is in front and the machine is not busy. A background tab, power saving or a second monitor can give a different number.
How is this different from TestUFO or other precise tools?
Precise tools run longer, compare frames on screen and use motion patterns you can check by eye. This page only counts how often your browser asks to draw a frame, so it shows what the browser gets, not what a camera would see on the panel.
Why does my 144Hz monitor show 60Hz?
The system may be set to 60 Hz, the cable or port may not support more, power saving may be on, or the window may sit on another monitor. Check your display settings first.
Does it work on phones?
Yes. Many phones run at 60 or 120 Hz and some lower the rate to save battery, so the number can change between runs.