VRR Flicker Test
Some G-Sync and FreeSync monitors pulse brighter and darker as frame rate swings around, because backlight drive is tied to refresh interval on those panels. This drives an irregular frame rate at your display so you can watch for it yourself.
This is a browser best-effort, not a lab instrument. It only reaches your panel as true VRR if your GPU driver forwards variable refresh to windowed content, not only exclusive fullscreen games. See the FAQ below to check that setting.
Smoothly ramps frame rate up and down across your full range, like RTINGS' method
How to read this
- No flicker: the fill stays a steady, unchanging brightness regardless of the fps counter moving.
- Flicker present: you see the whole screen pulse, breathe, or strobe brighter and darker in time with the frame rate changing.
- Try Threshold mode first with your panel's published VRR range minimum, since that boundary is where LFC-related flicker is worst.
- Turn VRR off in your GPU driver and repeat the same mode. If the pulsing stops, it confirms VRR is the cause rather than PWM or something else.
Testing guide
How to test for VRR brightness flicker
On some G-Sync and FreeSync panels, backlight or panel drive strength is tied to the instantaneous refresh interval, so a frame rate that swings around makes the whole screen visibly pulse brighter and darker. RTINGS tests this in a lab with a light meter; this reproduces the same idea by driving your own display through the same kind of irregular frame rate.
Best for
- Checking whether a monitor you own, or are considering buying secondhand, has VRR brightness flicker.
- Isolating whether visible pulsing in games comes from VRR specifically rather than PWM or a panel fault.
- Finding the exact frame rate range where flicker starts on your panel, so you know when to expect it in real games.
How to run the test
- 1Go fullscreen and start with Sweep mode on the mid gray pattern, which is the most sensitive combination.
- 2Watch for the whole screen pulsing, breathing, or strobing brighter and darker as the fps counter moves.
- 3Switch to Threshold mode and set the low end to your panel's published VRR range minimum, since LFC engaging and disengaging there is the most common trigger.
- 4Turn VRR off in your GPU driver and repeat the same mode; if the pulsing stops, VRR is confirmed as the cause.
How to read the result
A steady, unchanging fill with no visible pulsing means this test did not find flicker, though a lab measurement could still find a subtler version.
Visible pulsing that tracks the frame rate counter moving is the flicker signature; it usually gets worse the wider the swing between low and high fps.
If flicker only appears in Threshold mode near your VRR minimum, that points specifically at Low Framerate Compensation rather than VRR in general.
Related tools and guides
Frequently asked questions
What causes VRR brightness flicker?
On some panels, the backlight or panel drive strength is tied to the instantaneous refresh interval rather than held constant. When frame rate swings around, especially near the bottom of the VRR range where Low Framerate Compensation engages and disengages, that drive strength changes too, and the whole screen visibly pulses brighter and darker.
Does this test work like a real lab measurement?
No, and it does not claim to. RTINGS uses actual games and a light meter to measure output brightness precisely. This is a browser reproduction of the same idea, closest in spirit to an open-source OpenGL desktop tool that does something similar, and it depends on your setup actually forwarding the irregular timing to the panel.
Why does the test say it needs a driver setting enabled?
A web page cannot force VRR by itself. Your GPU driver has to be set to allow variable refresh rate for windowed or all content, not only exclusive fullscreen games, for a browser tab to have any chance of reaching the panel with irregular timing at all.
How do I enable VRR for windowed content?
On Windows 11, go to Settings, System, Display, Graphics, and turn on Variable Refresh Rate. On Nvidia, open Nvidia Control Panel, Display, Set up G-SYNC, and choose the option that enables it for windowed and full screen mode rather than full screen only. On AMD, enable FreeSync globally in Radeon Software rather than per game.
My monitor flickers in games but not in this test, why?
Real games produce far messier frame timing than any controlled pattern, and your browser may not be getting VRR treatment for windowed or tabbed content even with the right driver setting. A negative result here does not rule out flicker in real gameplay, only that this particular reproduction did not trigger it.