SDL_GetWindowPixelDensity - Man Page

#include <SDL3/SDL_video.h>

float SDL_GetWindowPixelDensity(SDL_Window *window);

This is a ratio of pixel size to window size. For example, if the window is 1920x1080 and it has a high density back buffer of 3840x2160 pixels, it would have a pixel density of 2.0.

window

the window to query.

Returns the pixel density or 0.0f on failure; call SDL_GetError() for more information.

This function should only be called on the main thread.

This function is available since SDL 3.2.0.

SDL_GetWindowDisplayScale(3)