Resolution vs FPS Estimator
Estimate how your frame rate changes when you move to a higher or lower screen resolution, free online.
About this calculator
When a game is GPU-bound, frame rate scales roughly with the inverse of the pixel count, though real results are usually a bit better than this worst case. Going from 1080p to 1440p increases pixels by 78% (≈ 56% of the fps) and to 4K by 300% (≈ 25–35%).