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Refresh Rate Test

See your screen’s real Hz right now, then check for skipped frames and flicker.

  • Free, no sign-up
  • Starts on its own
  • About 5 seconds

Step 1 · Live reading

Measured refresh rate

…Hz

Measuring. Keep this tab in front and hold still.

…Exact average
…Frame time
…Stability
…Skipped frames (last 240)
Several monitors? Drag this window to the other one and measure again.

Step 2 · Motion and frame skipping

Motion test

The block should glide. Jumps or stutter mean skipped frames. For a strict check, photograph the row of squares at 1/10 s exposure: every square should be lit evenly.

Step 3 · Flicker check

PWM flicker camera check

A browser can’t measure flicker. Your phone camera can hint at it. Open a plain screen, point the camera at it, and look for dark bands rolling across.

→ or tap: nextEsc exit

No full-screen mode in this browser. Safari on iPhone and some TV browsers can’t hide their bars, so the test fills the visible screen. Rotate the phone and scroll slightly to check the edges.

By GigaScreens Team · Updated 2026-10-17

Browser support: Tested in Chrome, Firefox and Safari (WebKit) on desktop and in iPhone and Android emulation. Real-phone checks are pending.

How the refresh rate test works

Browsers draw a new frame each time the screen refreshes, and they tell the page when they do it. The MDN docs for requestAnimationFrame say this generally matches the display’s refresh rate. The tool times the last 240 frames, takes the average, and rounds it to the nearest standard rate.

So the number is what your browser is actually getting right now. That’s often more useful than the box. A 165 Hz monitor running at 60 Hz shows 60 here.

Stability tells you how even the frames are. Low stability usually means the computer is busy, the tab lost focus, or a power-saving mode kicked in.

How to read the motion test

Press Start motion test and watch the lime block. At a high refresh rate it should look smooth and fairly sharp. Regular jumps or a stutter every second or so point to skipped frames.

The row of squares lights one square per frame. Screenshots won’t catch it. Take a phone photo at about 1/10 second exposure, the method Blur Busters’ TestUFO frame skipping check uses, and look for gaps in the lit row. Even squares mean no skipped frames.

For deeper motion tests (pursuit camera, ghosting, strobe crosstalk), TestUFO is the reference tool. This page is the quick check.

Stuck at 60 Hz? Quick checks

Plenty of 144 Hz monitors spend their whole lives at 60 Hz because nobody told Windows. Check these in order. The first two take a minute.

  1. Windows setting. Go to Settings > System > Display > Advanced display, pick the monitor, then choose a rate under “Choose a refresh rate” (Microsoft’s guide). An asterisk means that rate needs a different resolution.
  2. Mac setting. Apple menu > System Settings > Displays, select the display, then use the Refresh Rate menu (Apple’s guide).
  3. Cable and port. The rates on offer depend on the monitor, the graphics hardware and the connection, so use the cable that came with the monitor. On a desktop, plug into the graphics card, not the video port on the motherboard.
  4. Graphics driver. Update it from NVIDIA, AMD or Intel, then check the setting again. New drivers sometimes reset it.
  5. Laptop on battery. Plug it in and measure again. Windows can lower the refresh rate to save power on some laptops (Microsoft’s notes on Dynamic Refresh Rate).

Phones are trickier. Safari has capped web animation at 60 Hz on some ProMotion iPhones (WebKit bug 272165), and low-power modes can lower it further. A 60 Hz reading on a 120 Hz phone is often the browser, not the screen.

Screen flicker and PWM: what this can and can’t tell you

PWM (pulse-width modulation) dims a screen by switching the light on and off very fast instead of turning it down. Most people never notice. Some find it tiring.

No website can measure PWM. The browser only knows when it drew a frame, not what the backlight did. The camera check above is a hint, nothing more: rolling bands can also come from room lighting, so turn off overhead lights first.

Lower brightness is where PWM tends to show. In an RTINGS video on TV flicker, a Samsung KS8000 didn’t flicker at max backlight but did once the backlight was turned down. So run the check at your usual brightness, then a few steps lower.

If you’re shopping for a low-flicker screen, look for a review that measured it with proper equipment. RTINGS explains its approach on its image flicker test page. And if screens give you headaches, mention it to an eye doctor. This page can’t diagnose anything.

Whole-screen flicker, blinking to black or flashing lines is a different problem. That’s usually the cable, the refresh setting or the driver. The monitor flickering fix guide walks through it.

Frequently asked questions

Is an online refresh rate test accurate?

It measures how often your browser draws frames, which generally matches the display refresh rate. It’s accurate for what the browser gets right now. Background tabs, battery saver and busy computers can pull the number down, so measure twice.

Why does my 144 Hz monitor show 60 Hz?

Usually the Windows or Mac display setting is still at 60 Hz, or the cable or port can’t carry the higher rate. Check Settings > System > Display > Advanced display on Windows first.

Why does my 120 Hz phone show 60 Hz?

Some browsers, including Safari on some ProMotion iPhones, cap web pages at 60 Hz. Low-power modes can lower it further. The screen itself may still run at 120 Hz in apps.

Can a website detect PWM flicker?

No. A browser can’t see what the backlight does between frames. A phone camera can hint at it with rolling dark bands, but a proper measurement needs a light sensor.

What’s the difference between Hz and FPS?

Hz is how many times per second the screen refreshes. FPS is how many frames per second a game or app produces. A 144 Hz screen can only show up to 144 new frames a second.

Sources