Refresh Rate Test — Free UFO Hz Check & Monitor FPS Accuracy
Check your monitor's actual refresh rate using requestAnimationFrame. Detects frame skipping with UFO motion test. Shows resolution, DPI, and HDR info.
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
- ✓Frame time (input lag indicator) — displays the rendering time per frame in milliseconds, helping gamers understand the actual delay between GPU output and display refresh
- ✓VRR (Variable Refresh Rate) detection — monitors Hz fluctuations during the test to indicate whether FreeSync or G-Sync is actively synchronizing the refresh rate with content
- ✓Statistical histogram — shows the distribution of measured refresh rates across the test session, making it easy to spot instability patterns like inconsistent frame pacing
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
- 8Watch the frame time (ms) reading — lower frame times mean less input latency. For competitive gaming, a consistent frame time below 6.94ms (for 144Hz) is ideal
Frequently Asked Questions
How accurate is this refresh rate test?
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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?
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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?
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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?
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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?
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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)?
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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?
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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?
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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.
What is the difference between 60Hz, 120Hz, 144Hz, and 240Hz displays?
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A 60Hz display updates the image 60 times per second (one frame every 16.67ms). 120Hz updates every 8.33ms, 144Hz every 6.94ms, and 240Hz every 4.17ms. The perceived difference: 60Hz to 144Hz is a dramatic improvement in smoothness and reduced motion blur. 144Hz to 240Hz offers diminishing returns — noticeable to competitive gamers but less obvious to casual users. Higher refresh rates also reduce input lag because the display polls for new frames more frequently.
Why does my refresh rate fluctuate during the test?
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Fluctuations can be caused by: 1) Background processes consuming CPU/GPU resources. 2) Thermal throttling — if your GPU gets too hot, it may temporarily reduce performance. 3) Variable Refresh Rate (FreeSync/G-Sync) actively changing the refresh rate. 4) Power saving features on laptops that dynamically adjust display refresh. 5) Multiple displays connected to the same GPU sharing bandwidth. The statistical histogram shows the distribution of Hz values — a tight cluster around one value is healthy; wide variation suggests instability.
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