Refresh rate test

Why does it say 60?

A screen sold as 120, 144 or 240 Hz very often runs at 60 until something is changed. Check these in order, and press Start again after each one.

1. The display setting. Windows and macOS often leave a new monitor at 60 Hz: on Windows 11 go to Settings, System, Display, Advanced display and pick the rate next to Choose a refresh rate; on a Mac open System Settings, Displays and use the Refresh Rate menu.
2. The cable or port. A high rate at a high resolution needs a cable and port with the bandwidth for it, so if the rate you want is missing from that list, plug into the monitor's DisplayPort or its fastest HDMI port with the cable that came in the box.
3. A laptop on battery. Laptops lower the panel's rate to save power (Microsoft's own help says a lower rate saves battery), so plug the charger in and set the power mode to best performance before you measure.
4. Phone power saving. Samsung's Power saving mode sets the screen to Standard (60 Hz), and the iPhone setting Limit Frame Rate (Accessibility, Motion) caps a ProMotion display at 60, so turn both off.
5. The browser's own frame cap. Safari on iPhone draws pages near 60 fps by default even on a 120 Hz screen, and Google says Chrome's Energy Saver can change gaming and video performance, so the browser may be the only thing holding the number down.
6. A second monitor at a lower rate. With two screens, the reading belongs to the one this window is on, so drag the window fully onto the fast monitor, and if it still reads the slower screen's rate, run the test once with the other screen unplugged.

Worked example (an illustration of the steps, not a measurement): a 144 Hz monitor on a desktop reads 59.9 Hz, ≈ 60 Hz. Windows' Advanced display page lists only 60 Hz, which points at the connection, not the setting. Swapping a borrowed HDMI cable for the DisplayPort cable from the box adds 144 Hz to the list; after choosing it, the page reads 143.9 Hz, ≈ 144 Hz, and a 10-second run shows 1,439 frames and 0 skipped.

How to test your refresh rate

1. Open this page on the screen you want to test. On a computer, drag the window onto that monitor; close other busy tabs.
2. Wait two seconds. The big number is the measured rate to 0.1 Hz; the line under it is the nearest common rate, such as ≈ 144 Hz. A 59.94 Hz reading is a normal 60 Hz screen.
3. Press Start 10-second test and keep the mouse and keyboard still. Each bar on the graph is one frame; red bars are skipped frames.
4. Watch the motion test at Medium, then Fast. Use Full screen for a cleaner view; press Esc to leave.
5. If the rate is lower than the screen's rating, work through Why does it say 60? above and run the test again.

Reading the result

The browser hands the page a timestamp for every frame it draws. The page keeps the gaps between those timestamps for the last 2 seconds and takes their median: at 144 Hz that is 6.94 ms, at 120 Hz 8.33 ms, at 60 Hz 16.67 ms. The median ignores the odd slow frame, so one hiccup does not drag the number down. A skipped frame is a gap more than 1.5 times the median, which at 60 Hz means about 25 ms or longer: the screen showed the same picture twice. A few skipped frames in 10 seconds while other programs run is normal; dozens, or a regular pattern of them, show up as stutter in games and scrolling.

What it cannot do

• It measures what the browser draws, and a browser can cap that below the screen's rate (Safari on iPhone does by default, see above). A low number is the rate this browser gets, not proof the panel cannot do more.
• It cannot change your refresh rate; only your system, display or browser settings can.
• It cannot measure response time or input lag. The motion test lets you see smearing by eye; measuring it needs a camera or a sensor on the screen.

Privacy

Nothing leaves your device and nothing is saved. The page sends an anonymous page-view count and one fixed word, hz-start, when you press Start; never your reading.

Questions

How do I check my monitor's refresh rate?

Open this page in the browser window on that monitor and wait two seconds: the big number is the rate the browser is drawing at, and the line under it snaps it to the nearest common rate, such as ≈ 144 Hz. Then press Start for a 10-second run that counts skipped frames. If the number is lower than the monitor's rating, set the rate in Windows (Settings, System, Display, Advanced display, Choose a refresh rate) or on a Mac (System Settings, Displays, Refresh Rate) and measure again.

My 144 Hz monitor reads 60 Hz. Why?

Usually the operating system is still set to 60 Hz, the cable or port cannot carry 144 Hz at that resolution, or the browser window is on a second, slower monitor. Go through the checklist on this page one item at a time and press Start again after each change; when the reading jumps to about 144, you have found the cause.

Does this refresh rate test work on mobile?

Yes. It runs in any phone browser, and the reading is the rate that browser draws the page at. Phones lower that rate to save power, so if it reads 60 on a 120 Hz phone, check the power saving and display settings listed on this page, keep the phone plugged in and the screen moving, and measure again.

Why does my 120 Hz iPhone read 60 Hz in Safari?

Safari on iPhone draws web pages near 60 frames per second by default, even on ProMotion models; a WebKit engineer confirmed in 2024 that pages reach 120 fps only with the Safari feature flag Prefer Page Rendering Updates near 60fps turned off. It is under Settings, Safari, Advanced, Feature Flags. The Accessibility setting Limit Frame Rate also caps a ProMotion display at 60. This page measures what Safari draws, so it shows 60 until those change.

How do I test a 120 Hz Android phone?

Open the page in Chrome or Samsung Internet and read the number after two seconds. On Samsung Galaxy phones, Motion smoothness set to Standard means 60 Hz, Adaptive goes up to 120 Hz, and Power saving mode sets the screen to Standard, so it reads 60 when either is on. Turn Power saving off, choose Adaptive or High, and run the 10-second test while touching nothing.