Proper size (United States) flag to fly

Are there any rules of proper flag etiquette regarding how large a flag you’re supposed to display? I thought it rather gauche when I realized that a local car dealer’s flag is actually larger than the one over the State capitol.

The only size rule with the US flag is that it should not be displayed next to any larger flags.

He is some info about flag sizes.

Like with so many things in life, it all depends on the size of your flag pole.

Your ensign should be one inch for every foot of LOA. Use the next larger standard size if you have, say, a thirty-two footer.