A gallon jar can hold about 5,000 pennies, which is worth about $50. But, the number of pennies that will fit in a jar depends on where each penny is placed.
The thrifty saver can also weigh the contents of a gallon jar to get an idea of how many pennies are in it. For instance, first weigh the empty gallon jar, then fill it with pennies. Estimating that each penny weighs 2.5 grammes, the saver can weigh the jar full of pennies, subtract the weight of the empty jar, and divide the remaining weight in grammes by 2.5 to find out how many pennies are in the jar.