How the comparison works
Each component can only deliver so many frames per second in a given game and setting. The pair runs at the lower of the two figures, because the slower side cannot be pushed past its own limit.
The imbalance is the gap between the two as a share of the faster one. A large gap means one component is doing work the other cannot use.
Worked example
A processor that sustains 180 fps and a graphics card that sustains 120 fps give an expected 120 fps. The graphics card is limiting, the imbalance is 33.3 per cent, and the processor has 33.3 per cent headroom at that rate. The target of 60 fps is met.
If the card sustained 180 and the processor 120, the same numbers would point at the processor instead.
Why both figures must come from benchmarks
A bottleneck depends on the game, the resolution, the settings and the drivers. The same pair can be balanced at 1080p and entirely card-limited at 4K, because resolution changes the load on the card but barely changes the load on the processor.
This page holds no parts database. A generic percentage for a named processor and card would be a guess dressed as a measurement.
Limits of this calculator
It assumes both figures describe the same game, resolution and settings. Mixing figures from different reviews gives a meaningless answer.
It does not model frame pacing, memory capacity, storage speed or thermal throttling, any of which can dominate the result in practice.
To turn a frame rate into frame time, use the FPS calculator.
Inputs for the bottleneck calculator
Frame rate the processor can sustain
From a review of your processor at the resolution and settings you use.
Frame rate the graphics card can sustain
From a review of your card in the same game and settings.
Frame rate you want
Your target, so the page can say whether either component falls short.
CALCULATOR QUESTIONS
Bottleneck calculator questions
Why can I not pick my parts from a list?
A list would need a benchmark database that goes stale and covers few combinations. Entering two measured figures gives a real answer.
Does resolution change the bottleneck?
Yes. Higher resolution loads the graphics card and barely changes the processor, so the balance shifts.
What is a good imbalance?
Small. Within about 10 per cent the two are effectively matched; beyond that one is clearly limiting.
Can I fix a processor bottleneck with a better card?
No. The processor sets the ceiling, so a faster card adds little until the processor is upgraded.