So wear a bra when measuring yourself! Measure around underneath your boobs, if it’s an odd number (in inches) add 5, an even number, add 4... to measure your cup size, measure around your boobs and for every inch more than the bottom measurement, it’s a cup size..... for example: 33 inches would be a 38 (back size) for the first measurement, then if the cup measurement is 39, that would be an E cup (33+6). Does that make sense? Bear in mind, different style bras will fit differently: you may find you have to go up a cup in a balcony, but down a cup in a full cup style. A good bra should be on the loosest hook when you first wear it, the wires between the cups should sit flush to your chest. There should be no digging and the back shouldn’t rise up. Just because that’s what you measure as, it’s more a guideline. But if it helps until the stores are open again, it’s something! Hope that helps!