That totally depends on the size of the collage.
An 8×10 collage can support approximately three to four images —the main (large) image — and two to three smaller photos. If I add more images, they become small and hard to see.
For an 11×14 collage (or larger), I suggest five to seven images. Five or six images allows us to design for maximum visual impact. Too many photos will make the design busy and visually cluttered.
Take some time to look through the examples of collages I’ve designed and the collage templates before you place your order.