@Mrb53004 indoor is 1 gallon for every 30cm/1foot outdoor is 2 gallons for every 30cm/1foot.
Indoor 5 foot plant 5 gallon pot. Outdoor 5 foot plant 10 gallon pot.
The doubling in size from indoor to outdoor is to compensate for the increased light intensity and larger root balls as well as adding the extra soil/nutrients needed for the increased yield outdoor.
Choose your container size based off of average size of cultivar.