The average hot tub has walls that extend 5 – 6 inches above the water line, adding a little extra height. For example, a 36 -inch tub has a depth of 31 inches and a 42 -inch tub has a depth of 37.5 -inches.Click to see full answer. Similarly, what are the average dimensions of a hot tub? Choosing a Hot Tub Based on Size Hot Tub Size Ranges Length Width Small (2-4 people) 5’4” – 7” 5’4” – 6’8” Medium (5-6 people) 6’6” – 7’9” 6’4” – 7’9” Large (7+people) 7′ – 9” 7′ – 9’2” Subsequently, question is, how big is a 4 person hot tub? Four-person round hot tubs often range from 78 to 79 inches, but this can vary depending on the manufacturer. Considering this, how deep is a spa? about 3 feet How big is a 10 person hot tub?Measuring 3.8 metres in length, it is the only spa in the professional range that can hold up to 10 people.