Hammer CalculatorCalculators / Pools / Hot Tub Volume
Hot Tub / Spa Volume Calculator
Estimate water volume, seating capacity, fill time, and water cost for any hot tub or spa shape — round, square, or rectangular.
Hot Tub / Spa Volume Calculator
Water Pricing (edit to match local rates)
Hot Tub View
Volume
864 gal
3,269 liters
Seat Estimate
10 people
~22 ft perimeter
Fill Time
1.6 hrs
at ~9 GPM garden hose
| Purchase Option | Quantity | Est. Cost |
|---|---|---|
| Volume (gallons) | 864 | |
| Volume (liters) | 3,269 | |
| Volume (cu ft) | 115.5 | |
| Estimated seating | 10 people | |
| Fill time (~9 GPM hose) | 1.6 hrs | |
| Water cost per fill | $4.32 |
864 gallons — $4.32 per fillThis is a large spa. At 864 gallons, expect higher chemical and heating costs but plenty of room for 10 people.
Drain and refill scheduleMost hot tub manufacturers recommend draining and refilling every 3–4 months to keep water chemistry balanced. At 864 gallons, budget roughly $12.95–$17.27 per year in water costs alone (3–4 refills), plus chemicals and heating.
This is an estimate based on simple geometric shapes. Actual hot tub volumes vary due to seats, jets, curved walls, and internal plumbing. Consult manufacturer specs for exact capacity.