Piggy banks usually have the size of 1-2 inches. On average, they can hold $35 to $40 in coins. Since we mean piggy banks for children who are not yet familiar with the concept of saving money, they are usually only capable of holding a little number of coins inside them.
Weight is also an important factor to consider when buying piggy banks for children. You should also check if the piggy bank is portable and can be easily carried around by children.