The term "standard size" doesn't have a definitive answer when it comes to bags. This is because there is no industry-wide "standard" size for bags. Depending on the type of bag, there can be a range of sizes that are considered "standard" or "average." For example, a standard size for a carry-on bag is 22in x 14in x 9in, but a standard size for a duffel bag is 28in x 14in x 13in. So it really depends on the type of bag you're talking about. Hope this helps!