particle size much smaller than base image

The circle on the left is a sprite, (512x512px) the circle on the right is a particle system using the same image - all scaling is at 1. Why is the particle much smaller than the base image?

 

Bumpity

 

Is the one of left SpriteRenderer sprite or canvas Image?
Size of particle depends on:

• start size (in particle system core settings)
• size over lifetime
• size by speed
• possibly RenderMode (Renderer category)
• actual sprite geometry used for rendering instead of the rectangle selected in sprite editor (can cause particles to bigger than your calculations, if not taken into account
• there is some kind of maximum particle size relative to screen (not sure if it's configurable) but I have seen particle size change when you try zooming in and viewing the particle closer

Not sure about pixels per unit (in texture import settings), since I usually use 1, but I wouldn't be surprised if it didn't affect particles.

 

in particle renderer there's also Max Particle size (based on viewport)