A: Every dealer and manufacturer should provide you with the outside measurements of their hottubs. Carefully measure the area where you'd like the spa to sit, and compare it with the outside dimensions.
Remember to include room for your spa's step, and any wood surrounds, gazebos, or extra additions that you'd like to add. Also remember that if you're placing the spa inside a deck, or lowering it into the ground, you'll need to leave access on two sides for future repairs or service work.