GPU Stress Test
Load a WebGL scene in the browser. FPS, frame time and 1% lows are how fast this page presents frames, not a game or 3DMark score. Run all four levels for a score on this page, and read the GPU name when the browser shows it.
Press Start to load the GPU, or Benchmark to run all four levels for 10 s each.
FPS drift compares the last minute with the first minute after a 10 s warm-up. It appears after 2 minutes of frames while this tab is visible. Hidden time is left out. A steady drop of 10% or more means the frame rate fell. This page cannot read temperature, clocks, watts or fan speed.
Browsers sync drawing to the screen, so FPS cannot go above your refresh rate (60, 120, 144 Hz...). If Light and Medium sit exactly at that number, the GPU is not working hard yet. Use Heavy, Extreme, the heavy shader, or the device pixel ratio scale to push it below the cap.
Your GPU, as the browser sees it
Reading GPU details...
Is the GPU in that used PC what the listing says?
How the test works
The page draws thousands of spinning cubes in one instanced call, each lit by up to 32 moving lights in the fragment shader, and can add a full-screen ray-marched fractal whose step count you set. Each level multiplies the work. FPS, frame time and the 1% low (the average of the slowest 1% of frames, which shows stutter) come from the browser's frame clock. The benchmark runs each level for 10 seconds, ignores the first second, and weights the heavy levels most.
Check the renderer before you pay
The renderer line is a useful check on a used laptop or desktop when the browser exposes a name. A listing that says RTX 3060 should then show NVIDIA GeForce RTX 3060, not Intel UHD Graphics or AMD Radeon Graphics, which are integrated chips. If the name is hidden, this page cannot confirm the chip. On laptops with both, the browser may pick the integrated one: in Windows open Settings, System, Display, Graphics, add the browser and choose High performance, then reload. A lower score than another run of the same scene can be the browser, the power plan, or a different chip. It does not by itself prove a worn card or a failed fan.
What a browser test can't do
This is not FurMark or 3DMark. WebGL runs through the browser and often a translation layer (ANGLE to Direct3D or Metal), so scores are lower than a desktop app and differ between browsers. FPS here is how fast this page presents frames, and it is capped at your refresh rate. The browser can hide the GPU name. It cannot read temperature, clocks, watts or fan speed. A system tool such as HWiNFO or GPU-Z can show those while the page runs.
If the frame rate falls
Run Heavy or Extreme for 10 to 15 minutes and watch the chart. A flat line means the presented frame rate held. A slide over several minutes can mean the GPU is slowing down, which is common in thin laptops, but this page cannot read temperature, clocks, watts or fan speed, so it cannot show why. Plug laptops in, keep vents clear, and stop if the system shuts down, shows artifacts or smells hot. If the context is lost, the test stops. Use a lighter level. For CPU load use the CPU stress test.
Related tools
Load the processor with the CPU stress test, check smooth playback with the FPS test, confirm the screen runs at its rated speed with the refresh rate test, and look for smearing with the monitor ghosting test.
Frequently asked questions
Is this a game benchmark or a 3DMark score?
No. The page draws a WebGL scene and counts how fast the browser presents frames. The score is average FPS times a weight for each level on this page only. It is not a game result and not a 3DMark score. A 60 Hz screen can cap every level, which caps the score at 900.
What does the FPS number measure?
It is how fast this page presents frames, taken from the browser frame clock. It is not the frame rate of a game. Browsers usually present at most one frame per screen refresh, so the number will not rise past the refresh rate.
Why is the GPU name missing or vague?
The browser often hides the graphics chip. Safari may report every Mac and iPhone as Apple GPU. When the name is hidden, this page says so instead of guessing. A shown name is the chip the browser is using, which on a laptop can be the integrated one.
Can this page read temperature, clocks, watts or fan speed?
No. WebGL does not expose temperature, clocks, watts or fan speed. A drop in FPS can mean the GPU is slowing down, but the chart cannot show why. Use a system monitor if you need those readings.
Why do I see a dash instead of 0 FPS?
An empty sample is not 0 FPS. Before the first measured frames, and when a 1% low does not have enough frames yet, the readout is a dash. A hidden tab is left out, so those slow timers are not stored as a low average.
What are the resolution choices?
WebGL cannot read the panel native resolution. 0.5x and 1x set the drawing buffer from the canvas CSS size. The device pixel ratio option multiplies that CSS size by the screen pixel ratio. The numbers on the page are the drawing buffer, in pixels, not a display mode.
What if I leave the tab or the picture freezes?
A hidden tab is not scored. The benchmark stops, and a free run ignores frames from the time the tab was in the background. If the driver drops the WebGL context, the test stops and a message is shown. The loop does not keep spinning. Start again with a lighter level or the 0.5x scale, or reload the page.