image sizes

[mekgacom]

Good day
Please help me
Some how I messed up with the image sizes
What size should the “categories” image be when there are 3 columns?
Then what size should the “home page” image be?
And then the “product” image size as well?

[leo]

categories: 175x175
home page module width is 600px
Product Image Width and Height: 250x250