FPS test
Live counter showing how many frames your browser is actually rendering. Watch the number drop when you open another tab — that is your CPU throttling.
How to read this
The big number is the most recent measurement (updated every 100 ms). The 1-second average smooths out individual stutters. The 5-second average tells you the rate your browser sustains under continuous load. Min and max show the worst and best frame the test has captured since you started.
The bar chart is a 60-frame rolling history — when it dips, your browser hit a slow frame. Lots of small dips during scroll = bad UI; one big dip when you switch apps = OS context switch (normal).
FPS in plain English
FPS — frames per second — is how many distinct still images your screen shows you in one second of looking at it. Movies traditionally run at 24 FPS. Video games target 60 or 120. The reason "more FPS feels smoother" is that your eye and brain stitch consecutive still images into apparent motion; the more samples per second, the more accurately the motion is reconstructed.
This matters most for things that move quickly. A static page of text reads identically at 30 FPS or 240 FPS. A first-person shooter with fast camera movement is dramatically different at 60 vs 144 vs 240.
If your number looks low
- It caps at 60 — your monitor is 60Hz, or vsync is on, or you are on battery. See the refresh rate test to confirm.
- It is below 60 on a 60Hz screen — something else on your machine is using the GPU or CPU. Close other tabs, disable browser extensions, check Task Manager.
- It bounces wildly — likely thermal throttling. Laptops sustain high frame rates for a few minutes then drop as the CPU/GPU heats up. Clean the fans, raise the laptop off soft surfaces.
- "Add render load" tanks it — that is normal. The button animates 200 elements simultaneously to demonstrate what GPU stress feels like.
FPS vs refresh rate vs frame time
Three closely related concepts that mean different things:
- FPS — frames produced per second by software (game, browser, video player).
- Refresh rate — frames the screen can display per second. Hardware property.
- Frame time — milliseconds between consecutive frames. 60 FPS = 16.7 ms per frame; 120 FPS = 8.3 ms; 240 FPS = 4.2 ms.
FPS is capped at refresh rate (you cannot see frames the screen does not draw). Frame time is the most useful for spotting stutter — a steady 60 FPS feels smoother than a wobbly 90 FPS, because frame-time consistency matters more than raw average.