Most hot tubs hold a few hundred gallons. In the manufacturer spec sheets below, hard-shell tubs run from 190 gallons for a two-seat Hot Spring TX to 503 gallons at the fill line for an eight-seat Bullfrog A8. Inflatables are at the small end: 177 gallons for a Lay-Z-Spa Miami AirJet, and 210 to 354 gallons for Intex PureSpa sizes. Your exact number is on your model’s spec sheet or in its manual.
Hot tub capacity by model
| Model | Seats | Water capacity |
|---|---|---|
| Hot Spring TX | 2 | 190 gallons (720 liters) |
| Hot Spring Stride | 3 | 225 gallons (850 liters) |
| Hot Spring SX | 3 | 230 gallons (870 liters) |
| Bullfrog X5L | 3 | 217 gallons (821 liters), fill line |
| Hot Spring Relay | 6 | 340 gallons (1,290 liters) |
| Hot Spring Envoy | 5 | 390 gallons (1,475 liters) |
| Bullfrog X8 | 8 | 486 gallons (1,840 liters) |
| Bullfrog A8 | 8 | 503 gallons (1,904 liters) at the fill line; 644 gallons (2,438 liters) at max fill |
| Bestway Lay-Z-Spa Miami AirJet (inflatable) | 2–4 | 177 gallons (669 liters) |
| Intex PureSpa Bubble Massage (inflatable) | 4 / 6 / 8 | 210 / 290 / 354 gallons (795 / 1,098 / 1,340 liters) |
Seat count is only a rough guide. The five-seat Envoy holds 390 gallons, which is 50 gallons more than the six-seat Relay’s 340 gallons. Shape, depth and seat design matter more than the number of people.
How to find your hot tub’s gallons
- Look up the model. The model name is on your manual, receipt or dealer paperwork. The maker’s spec sheet lists water capacity.
- Use the fill-line figure. Bullfrog lists both a fill-line and a max-fill capacity; dose for the level you actually keep the water at.
- No model name? Measure it. Read your water meter before and after your next refill. The difference is what your tub holds at that level.
- Last resort: estimate from the table using a tub of similar size and seat count, and treat the result as approximate.
Skip the length-times-width-times-depth formula used for pools. Seats and footwells take up a lot of the shell, so a box calculation overstates a hot tub’s real volume.
Why the number matters
- Chemical doses are written per gallons of water, so a wrong volume means a wrong dose. See how to shock a hot tub for how doses scale. The hot tub dose calculator uses that volume for a rough estimate only; the product label decides the dose.
- Draining and refilling take longer the bigger the tub; timings are in how to drain and refill a hot tub.
For the full care routine, see the hot tub and spa care guide.
Sources
- Hot Spring Spas: Hot Spot TX spec sheet
- Hot Spring Spas: Hot Spot SX spec sheet
- Hot Spring Spas: Hot Spot Stride spec sheet
- Hot Spring Spas: Hot Spot Relay spec sheet
- Hot Spring Spas: Highlife Envoy spec sheet
- Bullfrog Spas: X5L model specifications
- Bullfrog Spas: X8 model specifications
- Bullfrog Spas: A8 model specifications
- Intex: PureSpa Bubble Massage Owner’s Manual (347IO, 2021; hosted by Intex UK)
- Bestway: Lay-Z-Spa AirJet Owner’s Manual (Miami, Cancun, Bahamas, St. Moritz, Helsinki; 2020)
Research checked 2026-10-14.
