Screen Soft Light / Diagnostics / REFRESH RATE TEST
-- Hz
Nearest standard rate
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Frame time (avg)
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Fastest / slowest
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Dropped frames
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Measuring...

Space pauses, arrow keys change speed, F goes fullscreen.

No. 001 · REFRESH RATE TEST

Refresh rate and ghosting test for any display

  • 01 Live Hz and frame time
  • 02 Dropped frame counter
  • 03 Ghosting test at 3 speeds

See how many frames per second your browser really gets from your screen. The tool shows the measured Hz, the frame time and the dropped frames, and a moving object at three speeds lets you look for ghosting and motion blur.

§ 01

How the measurement works

The page asks the browser for a callback before each frame is drawn, using requestAnimationFrame, and times the gap between callbacks. The median gap over the last two seconds gives the frame rate, and a gap noticeably longer than that counts as dropped frames. The browser paints at most once per screen refresh, so the figure is the rate your browser actually gets, which is what matters for web content.

§ 02

The number can never be higher than the display's current refresh rate, and it cannot show the panel's maximum if the system is set lower, so check your display settings if a 144 Hz monitor reads 60.

What the browser cannot tell you

The number can never be higher than the display's current refresh rate, and it cannot show the panel's maximum if the system is set lower, so check your display settings if a 144 Hz monitor reads 60. With variable refresh rate (G-Sync, FreeSync, ProMotion), the rate may follow the content and move around. Background tabs, battery saver and low power mode throttle frames, and some browsers cap the rate in certain windows. Results from phones and laptops on battery are often lower than the panel's rating.

§ 03

Ghosting, overshoot and motion blur

Ghosting is a faint trail left behind a moving object because pixels change colour too slowly. Overshoot (inverse ghosting) is a bright or dark halo in front of or behind the object, caused by response time overdrive that is set too high. Motion blur from the eye tracking a held image is separate: sample-and-hold displays smear motion even with instant pixels, and only strobing or black-frame insertion reduces it. Use the object at the speeds shown to compare monitors or overdrive modes side by side. For a camera test, take a photo with a shutter time of about 1/15 s while the object moves.

§ 04

Getting the refresh rate you paid for

Set the rate in the operating system (Windows: Settings, System, Display, Advanced display; macOS: System Settings, Displays), use a cable and port that support it (DisplayPort or HDMI 2.0 and above for 144 Hz at 1080p to 1440p), and turn off battery saver. External monitors on a laptop can be limited by the port, a dock or the integrated graphics. After changing, reload this page and check the Hz.

Procedure

Three moves to peak output

  1. 01

    Keep this tab in front

    Browsers slow down hidden tabs and windows. Keep the page visible and close heavy tabs and apps for a clean reading.

  2. 02

    Read the Hz number

    Wait a few seconds for it to settle. It should match the rate chosen in your system display settings.

  3. 03

    Watch the moving object

    Follow it with your eyes on each speed. Look for a faint trail behind it (ghosting) or a bright halo in front (overshoot).

  4. 04

    Compare modes

    Change the monitor's response time or overdrive setting in its menu and run the same speed again.

Inquiries

Questions worth asking

Q.01 How do I check my screen refresh rate online?
Open this page in a visible tab and wait a couple of seconds. The tool counts how often the browser draws a frame with requestAnimationFrame and shows the result in Hz, along with the average frame time and the number of dropped frames. A 60 Hz display reads about 60, a 144 Hz display about 144.
Q.02 Why does the test show 60 Hz on my 120 or 144 Hz monitor?
Either the operating system is set to 60 Hz, the cable or port cannot carry the higher rate, or the browser is limiting frames. Check Display settings (Windows: Advanced display, macOS: Displays) and make sure you are using DisplayPort or HDMI 2.0 and above. Low power mode on a laptop or phone can also cap the browser to 60 Hz or 30 Hz.
Q.03 Can a browser measure the real refresh rate?
Only approximately. The browser draws at most one frame per screen refresh, so it can never report more than the display runs at, and it cannot tell you the panel's native maximum if the system is set lower. Variable refresh rate (G-Sync, FreeSync, ProMotion) can make the number change with the content, and background tabs and power saving modes throttle frames. Treat the result as the rate the browser actually gets, not a lab measurement.
Q.04 What is a dropped frame and why do I see them?
A frame is counted as dropped when it takes clearly longer than the typical frame time, which means the page missed a refresh. A few drops while the page loads or when you switch tabs are normal. Constant drops usually come from a busy computer, many open tabs or a power saving mode.
Q.05 How does the moving object test ghosting?
A white object crosses a black background at a fixed speed. If the screen is slow to change pixels, you will see a faint trail behind the object, a ghost. Trails that are bright and long suggest slow pixel response, or an overdrive setting that is too high and causes a bright halo in front. Try the three speeds and compare the monitor's response time modes.
Cross-reference

Try adjacent plates