How many gallons in a 6×6 hot tub?
A 6 ft 6 in square hot tub, the usual “6×6”, holds about 260 gallons by the published-capacity estimate (likely 230 gal – 290 gal). Published models list 250 to 265 gallons.
How to work it out
- Outside footprint: 42.3 sq ft
- Fit through 18 published tubs: 10.9 × 42.3 sq ft − 200 = 260 gal
- Published tubs miss that line by up to 12%: 230 gal – 290 gal
Hot tubs sold as “6×6” or “6 ft” are usually 6 ft 6 in (78 in) square — the 4–5 person class. A true 6 ft tub is smaller, typically 3 seats and about 230 gallons.
Adjust for your project
- Likely range
- 230 gal – 290 gal
- Outside footprint
- 42.3 sq ft
- Published tubs about this size
- Hot Spring SX 230 gal; Hot Spring Excursion 250 gal; Hot Spring Monterey 265 gal; Caldera Bloom 265 gal
- The spec sheet or manual is the best source. Some makers list two figures — to the fill line and to the brim — and the fill-line number is the one to dose with.
Square hot tubs from 6 to 7 ft
| Size | Estimated gallons | Likely range |
|---|---|---|
| 6 × 6 ft | 192 gal | 170 gal – 214 gal |
| 6.25 × 6.25 ft | 225 gal | 199 gal – 252 gal |
| 6.5 × 6.5 ft | 260 gal | 230 gal – 290 gal |
| 6.75 × 6.75 ft | 296 gal | 262 gal – 331 gal |
| 7 × 7 ft | 334 gal | 295 gal – 372 gal |
Published capacities in the 6–6.5 ft class
Hot Spring SX (77 × 72 in): 230 gal; Hot Spring Excursion (78 × 78 in): 250 gal; Hot Spring Monterey (78 × 78 in): 265 gal; Caldera Bloom (78 × 78 in): 265 gal; Caldera Tarino (82 × 82 in): 310 gal.
- Small tubs heat up and cool down faster and swing in chemistry faster too — test before each use.
- Doses. At about 260 gallons, 1 ppm of chlorine is about 0.27 fl oz (8 ml) of 12.5% liquid chlorine, or about half a fluid ounce of 6% bleach — measure with a syringe or marked cup.
- Round 6 ft 6 in tubs (such as the Hot Spring Aptos) list about 265 gallons as well — a round tub of the same width fills more of its footprint.
- Drain and refill about 260 gallons takes roughly half an hour from a typical garden hose.
Next sizes up: how many gallons in a 7x7 hot tub and how many gallons in an 8x8 hot tub. Dosing a small tub: how much bleach to put in a hot tub.
Different size? Use the full Hot Tub Gallons Calculator.
What you’ll need
- Hot tub test strips (chlorine or bromine)Budget price
Hot tubs move faster than pools; a strip before each soak tells you whether the sanitizer is still there.
See options on Amazon (opens in a new tab) - Bromine tablets (BCDMH)Budget price
The usual hot tub bromine for a floater or feeder. Bromine holds up better than chlorine in hot water.
See options on Amazon (opens in a new tab) - Hot tub coverPremium price
A good cover keeps heat in and debris out. A waterlogged cover loses most of its insulation.
See options on Amazon (opens in a new tab)
As an Amazon Associate we earn from qualifying purchases. Links to products are affiliate links — they cost you nothing extra and help keep these calculators free.
Frequently asked questions
How many gallons in a true 6 × 6 ft hot tub?
About 192 gallons by the estimate (likely 170 gal – 214 gal).
How many gallons in a 6 ft 6 in round hot tub?
About 265 gallons, based on a published 6 ft 6 in round tub.
Other common sizes
- How many gallons in a 7x7 hot tub — 334 gal
- How many gallons in an 8x8 hot tub — 454 gal
Sources
- Hot Spring SX — manufacturer spec page (opens in a new tab) — 77 × 72 in outside, 230 gal.
- Hot Spring Excursion — manufacturer spec page (opens in a new tab) — 78 × 78 in outside, 250 gal.
- Hot Spring Monterey — manufacturer spec page (opens in a new tab) — 78 × 78 in outside, 265 gal.
- Caldera Bloom — manufacturer spec page (opens in a new tab) — 78 × 78 in outside, 265 gal.
- Caldera Tarino — manufacturer spec page (opens in a new tab) — 82 × 82 in outside, 310 gal.
- Hot Spring Rhythm — manufacturer spec page (opens in a new tab) — 84 × 84 in outside, 330 gal.
- Hot Spring Flair — manufacturer spec page (opens in a new tab) — 84 × 84 in outside, 335 gal.
- Hot Spring Relay — manufacturer spec page (opens in a new tab) — 84 × 84 in outside, 340 gal.
- Hot Spring Vanguard — manufacturer spec page (opens in a new tab) — 87 × 87 in outside, 375 gal.
- Bullfrog A7L (fill line) — manufacturer spec page (opens in a new tab) — 88 × 88 in outside, 368 gal.
- Jacuzzi J-285 — manufacturer spec page (opens in a new tab) — 89 × 89 in outside, 365 gal.
- Caldera Geneva — manufacturer spec page (opens in a new tab) — 89 × 89 in outside, 410 gal.
- Jacuzzi J-385 — manufacturer spec page (opens in a new tab) — 91 × 91 in outside, 460 gal.
- Cal Spas Cancun EC-849B — manufacturer spec page (opens in a new tab) — 93 × 93 in outside, 450 gal.
- Bullfrog A8L (fill line) — manufacturer spec page (opens in a new tab) — 94 × 94 in outside, 457 gal.
- Hot Spring Grandee — manufacturer spec page (opens in a new tab) — 100 × 91 in outside, 455 gal.
- Caldera Cantabria — manufacturer spec page (opens in a new tab) — 108 × 91 in outside, 615 gal.
- Hot Spring Prism — manufacturer spec page (opens in a new tab) — 110 × 91 in outside, 525 gal.
- Hot Spring Envoy — manufacturer spec page (opens in a new tab) — 5 seats on the same 8 ft 4 in × 7 ft 7 in footprint and 455 gal as the 7-seat Grandee.
- Hot Spring Aptos — manufacturer spec page (opens in a new tab) — Round, 6 ft 6 in diameter, 265 gal.
- CDC Healthy Swimming — Staying healthy in hot tubs (opens in a new tab) — No hotter than 104°F (40°C); chlorine at least 3 ppm or bromine 4–8 ppm.