yes they do mean from base of plant to the tip of the plant. just use approximate. don't have to be totally accurate. If you were to use the size of the pot then plus the plant you would be off and never be very accurate. Pots come in many shapes and sizes and using the pot to measure would send you numbers off. always from the base to the top of the plant. remember that you plants can grow to 3Xs there size during flowing. So make sure the space you have them in can hold the plant times 3 for flowering.