UFO Test — See Motion Blur On Your Monitor

Every monitor refreshes its image a fixed number of times per second — that is your refresh rate in Hz. Between refreshes, the pixels are supposed to transition from one colour to the next as fast as the panel allows. When an object moves across the screen, each refresh moves it by a few pixels. If those pixels cannot change colour quickly enough, the previous frame's image lingers and your eye blends it into the new one. The result is a smeared trail that follows the moving object — what gamers call motion blur or ghosting.

The UFO test makes this invisible behaviour visible. By moving an object at a known speed, we can predict exactly how many pixels of blur a healthy panel should produce. At 960 pixels per second on a 60 Hz monitor, the object moves 16 pixels per frame. A perfect instant-response panel would show a sharp 16-pixel-wide object. A real IPS panel might show a 30-pixel smear. A budget VA panel might show 60 pixels of trail. The numbers translate directly into how readable moving text feels, how easy it is to track targets in a shooter, and how fatiguing fast camera movement becomes.

How to read the UFO test results

There is no pass-or-fail score — the UFO test is a visual benchmark. Here is what to look for at each speed:

• 120 px/s — Should look perfectly sharp on any modern monitor. If you see blur here, your panel is either faulty or the overdrive is way too aggressive.
• 480 px/s — Equivalent to a slow camera pan in a strategy game. A 60 Hz IPS panel will show a faint trail; a 144 Hz IPS panel should look clean.
• 960 px/s — The classic Blur Busters reference. Equal to a medium-speed pan in an FPS game. This is where most 60 Hz monitors fall apart and where 144 Hz+ monitors start to justify their price tag.
• 1920 px/s — Fast pan or flick aim. Even good 144 Hz monitors start showing ghosting here unless motion blur reduction (ULMB, ELMB, MBR) is enabled.
• 3840 px/s — Worst-case scenario, like aiming at a low-flying jet in Battlefield. Only ultra-fast TN panels and strobed LCDs hold up at this speed.

Why background colour matters

Pixel transition time depends on the start and end colours. Most monitors transition quickly from grey to grey (the number quoted in spec sheets) but slowly from black to white or between highly saturated colours. Use the grey background for a fair comparison against spec-sheet response times, then switch to red, green or blue to expose the panel's worst-case behaviour. A monitor that looks fine on grey but smears badly on red is a typical VA panel characteristic — and a useful warning sign if you play games with lots of red UI elements.

UFO test vs ghosting test — what's the difference?

They describe the same phenomenon from different angles. The UFO test shows multiple objects at different speeds to give you a benchmark sweep. Our ghosting test uses a single object so you can isolate one speed and one background colour. Both tools use the same underlying requestAnimationFrame loop — the difference is purely in how the data is presented.

Common UFO test results and what to do about them

Frequently asked questions