FPS and Performance
FPS, frame time and 1 percent lows: what to measure and why
Average FPS hides stutter. Learn what frame time and 1 percent lows tell you, how to measure them in your games and which numbers to aim for.
When people compare how well a game runs, they usually quote one number: average FPS. It is a useful start, but it can hide the thing that bothers you most, which is stutter. To judge performance properly you need two more ideas: frame time and 1 percent lows.
FPS and frame time
FPS, or frames per second, counts how many images the game draws in one second. Frame time is the other side of the same coin: how many milliseconds each frame takes. At 60 FPS every frame takes 16.7 ms, at 120 FPS it takes 8.3 ms and at 240 FPS it takes 4.2 ms. You can convert between them with our FPS to frame time calculator.
Frame time is the better way to see smoothness, because what you feel is whether frames arrive at an even pace. A game that averages 100 FPS but sometimes needs 50 ms for a single frame will feel rough, even though the average looks great.
Why the average can mislead
An average adds up everything and divides it. A few very slow frames hardly change it. Imagine one second with 99 frames of 8 ms and one frame of 200 ms. The average looks excellent, yet you saw a clear hitch. This is why reviewers show a second number next to the average.
What 1 percent lows are
The 1 percent low is the frame rate of the slowest one percent of frames. It describes how the game behaves at its worst moments. If the average is 120 FPS and the 1 percent low is 110 FPS, the game is steady. If the 1 percent low is 45 FPS, you will notice stutter, even with a high average.
Different tools calculate this a bit differently, so compare values from the same tool, not between tools.
How to measure it
- Many games have a built-in frame rate counter in their settings.
- Overlay tools from graphics card makers show FPS and frame time while you play.
- Free tools for logging performance can record a session and report averages and 1 percent lows afterward.
- Consoles and handhelds often have a frame rate option in the developer or accessibility menus of a specific game, but not always.
Test in a repeatable scene, such as a fixed route or a replay, and play for a few minutes so that the hardware reaches its normal temperature.
What numbers to aim for
- A steady 60 FPS with 1 percent lows above 50 is smooth for most games.
- For fast shooters, many players aim for 120 FPS or more with lows that stay close to the average.
- A frame time graph that is a flat line is better than one with spikes, even at a lower average.
What causes spikes
Common reasons for stutter are:
- Running out of video memory, which forces the game to use slower system memory.
- Loading data from a slow drive while you move through the world.
- A processor that cannot keep up in busy scenes.
- Background programs that wake up in the middle of play.
- Overheating, which makes the hardware slow itself down.
If you see spikes, read how to raise FPS in any PC game and check which component is the limit with our bottleneck guide.
Frame pacing and refresh rate
Even a perfect frame time can look uneven if the frames do not match the screen's refresh rate. A screen with variable refresh rate adapts to the game and hides small differences. Without it, cap the frame rate to a number that divides your refresh rate, such as 72 FPS on a 144 Hz screen. Our guide on monitor refresh rates explains why.
The short version
Look at three things: the average FPS, the 1 percent lows and the frame time graph. If the graph is smooth and the lows are close to the average, the game will feel good, whatever the headline number says.