How accurate is this refresh rate test?

The measurement uses requestAnimationFrame timing, which is the most accurate method available in web browsers. On most systems, accuracy is within ±1-2 Hz of the actual display refresh rate. Browser overhead, background processes, and power-saving features can cause minor fluctuations. For professional-grade accuracy, dedicated hardware tools like a oscilloscope or high-speed camera are needed, but this test is more than sufficient for consumer verification.

Why does my 144Hz monitor show 60Hz?

This usually means your monitor isn't configured to use its maximum refresh rate. Common causes: Windows display settings are set to 60Hz, the DisplayPort cable doesn't support the full bandwidth, the GPU driver needs updating, or you're using an HDMI cable that doesn't support high refresh rates. Go to your operating system display settings and manually select the highest available refresh rate. Also ensure you're using the cable that came with your monitor.

What is frame skipping and why does it matter?

Frame skipping occurs when your display or GPU fails to render a frame within the refresh interval, causing a visible stutter or gap in motion. On a 144Hz display, each frame has only 6.94ms to render — if the GPU takes longer, that frame is skipped. This is particularly noticeable in fast-paced gaming and smooth scrolling. Our test detects frame skips by monitoring the consistency of animation timing. Frequent frame skips indicate your system can't sustain the target refresh rate.

Does this work on phones and tablets?

Yes. Modern smartphones and tablets often have high refresh rate displays (90Hz, 120Hz, or even 144Hz). The test works on any device with a modern browser that supports requestAnimationFrame. On iOS, the Fullscreen API is limited, but the measurement and animation still function correctly in the normal page view. For best results on mobile, close other apps and ensure the device isn't in low-power mode, which may reduce the refresh rate.

Why is my measured Hz slightly different from the rated spec?

A small variance of ±1-3 Hz is normal and expected. Browser overhead, JavaScript execution time, and operating system scheduling all introduce minor timing variations. Additionally, some displays use variable refresh rate (VRR/FreeSync/G-Sync) which dynamically adjusts the Hz based on content. The measured value represents the average over the test duration. If the variance is large (more than 5 Hz), there may be a configuration issue or the display isn't running at its intended refresh rate.

Can I test variable refresh rate (FreeSync/G-Sync)?

This test measures the average refresh rate over time. If your display uses Variable Refresh Rate (VRR), the measured Hz may fluctuate as the refresh rate changes dynamically based on content. For a true VRR test, you need specialized hardware. However, you can observe VRR behavior by watching the Hz counter while the animation speed changes — on a VRR display, the refresh rate should adjust smoothly.

Will this test damage my screen?

No. The test uses standard browser animations that are completely safe for any display technology — LCD, OLED, LED, or CRT. The animations run for a limited time and do not produce static images long enough to cause burn-in. This is the same type of animation used by websites like testufo.com, which have been used safely by millions of users.

What should I do if my measured refresh rate is wrong?

First, close all other browser tabs and applications to reduce system load. Then check your display settings: on Windows, go to Settings > System > Display > Advanced Display; on macOS, go to System Settings > Displays; on Linux, check your display server settings. Ensure the highest refresh rate is selected. Update your GPU drivers to the latest version. If using DisplayPort, try a different cable. Some laptops automatically reduce refresh rate in battery mode — plug in the charger.

Tools

—

UFOs:

Speed:2x

Refresh Rate & Frame Time Reference

60 Hz16.7 ms

120 Hz8.3 ms

144 Hz6.9 ms

165 Hz6.1 ms

240 Hz4.2 ms

300 Hz3.3 ms

360 Hz2.8 ms

480 Hz2.1 ms

600 Hz1.7 ms

1000 Hz1.0 ms

• Lower frame time = smoother motion. Gamers target <6ms for competitive play.

• VRR (FreeSync/G-Sync) syncs GPU output to display refresh, eliminating tearing.

Refresh Rate Test — Free Online Monitor Hz & FPS Checker

Free online refresh rate tester to check your monitor's actual Hz. Measures real display refresh rate using requestAnimationFrame, detects frame skipping, and shows UFO motion test for visual comparison. Displays screen info including resolution, DPI, color depth, and HDR support. Works on all monitors, laptops, and phones with a modern browser — no download required. All testing runs locally in your browser for 100% privacy.

Features

✓Real-time refresh rate measurement — uses requestAnimationFrame timing to detect your monitor's actual Hz with high precision, updating live as you watch
✓UFO motion test — animated flying saucers move across the screen at different speeds to visually compare frame rates, inspired by the classic Blur Busters test
✓Frame skip detection — identifies dropped frames during measurement, alerts you if your display or GPU can't keep up with the target refresh rate
✓Multiple visualization modes — choose between UFO animation, bar chart, or raw number display to suit your testing preference
✓Display information panel — shows screen resolution, device pixel ratio, color depth, HDR support, color gamut, and orientation
✓Historical tracking — records peak, average, and minimum refresh rate across the entire test session for comprehensive analysis
✓Works on all displays — desktop monitors, laptop screens, tablets, and phones. Supports 60Hz, 120Hz, 144Hz, 165Hz, 240Hz, 360Hz and higher refresh rates
✓No installation required — runs entirely in browser, no software download or browser extension needed
✓100% private — all testing happens locally, no data sent to server

How to Use

1Close other browser tabs and resource-heavy applications for the most accurate measurement
2Click 'Start Test' to begin measuring your display's refresh rate
3Watch the UFO animation — smooth motion indicates your display is running at its native refresh rate
4Monitor the real-time Hz counter — it shows your display's current refresh rate updating every frame
5Check the frame skip indicator — any dropped frames appear as gaps in the animation or red warnings
6Review the session stats — peak, average, and minimum Hz give you a complete picture of your display performance
7Compare with your monitor's rated spec — if measured Hz is significantly lower, check your display settings and GPU configuration

Frequently Asked Questions

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