Frames per second and frame time
Frame rate (FPS) says how many images are drawn each second. Frame time is how long each one takes, in milliseconds:
Frame time (ms) = 1,000 ÷ FPS, and FPS = 1,000 ÷ frame time
Frame time is the more useful measure for performance tuning: the difference between 30 and 60 FPS is 16.7 ms, while the difference between 120 and 144 FPS is only 1.4 ms.
Reference table
| FPS | Frame time |
|---|---|
| 30 | 33.3 ms |
| 60 | 16.7 ms |
| 120 | 8.33 ms |
| 144 | 6.94 ms |
| 165 | 6.06 ms |
| 240 | 4.17 ms |
| 360 | 2.78 ms |
Matching your monitor
A monitor refreshes at a fixed rate (60, 144, 240 Hz…). If the game draws fewer frames than the refresh rate, some frames stay on screen longer, which shows as stutter; if frames arrive at random moments, the screen can show parts of two frames at once (tearing).
- V-Sync waits for the refresh, avoiding tearing but adding latency.
- Adaptive sync (G-Sync, FreeSync) makes the monitor follow the game’s frame rate within its range, the best option for most players.
- Frame caps a few FPS below the refresh rate keep adaptive sync active and reduce input lag.
Frame time consistency
Average FPS hides spikes. A game averaging 60 FPS with occasional 50 ms frames feels worse than a steady 50 FPS. Benchmarks report 1% low and 0.1% low FPS to capture these stutters, and tools such as MSI Afterburner or PresentMon can graph frame times.
Budgets for developers
At 60 FPS a game has 16.7 ms for everything: input, game logic, physics, rendering and presentation. At 120 FPS the budget halves to 8.3 ms. VR headsets need 90 FPS (11.1 ms) or more to avoid discomfort.
Video
Film uses 24 frames per second (41.7 ms per frame), European TV 25 (40 ms) and North American TV 29.97 or 30. For converting between frames and timecode, see the timecode calculator.