Is the photo size suitable for the competition?

It depends on the content of your performance and the resolution of the photo.

If it is a big scene, it is too small to show momentum;

If the resolution of the photo is not enough, it will be embarrassing to enlarge the details;

Generally speaking, 8 inches to 10 inch is enough.

Another suggestion: if you consider the cost of large size, you can also find a printing shop without printing paper, which is much cheaper.