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Steam Generator Sizing Calculator
Enter your shower or steam room size and wall material to see which Mr. Steam or Kohler steam generator fits. The result follows each manufacturer’s published sizing chart and links straight to the right size.
How steam generator sizing works
Start with the room volume: inside length × width × ceiling height, in feet. A 5 × 4 ft shower with an 8 ft ceiling is 160 cu ft. Then adjust for what the room is made of, because some materials soak up more heat.
Mr. Steam adjustments
- Ceramic or porcelain tile: no change.
- Natural stone, marble, glass block or concrete: add 50%.
- Acrylic or fiberglass: subtract 40%.
- Ceiling over 8 ft: add 15% for each extra foot, up to a 10 ft ceiling.
Pick the first size whose rating covers the adjusted volume.
| Mr. Steam model | Power | Room size (adjusted) |
|---|---|---|
| MS90 | 5 kW | up to 71 cu ft |
| MS150 | 6 kW | up to 107 cu ft |
| MS225 | 7.5 kW | up to 161 cu ft |
| MS400 | 9 kW | up to 257 cu ft |
| Super 1 | 10 kW | up to 339 cu ft |
| Super 2 | 12 kW | up to 411 cu ft |
| Super 3 | 15 kW | up to 482 cu ft |
| MAX MX4 | 20 kW | up to 678 cu ft |
| MAX MX5 | 24 kW | up to 822 cu ft |
| MAX MX6 | 30 kW | up to 964 cu ft |
Mr. Steam’s compact Steam@Home uses its own chart: 60 to 150 cu ft, tile or acrylic only, with ceilings up to 8 ft.
Kohler adjustments
Kohler sizes on the room volume alone, then goes up one generator size for each foot of ceiling over 8 ft (10 ft maximum). It does not publish an adjustment for stone or acrylic.
| Kohler model | Power | Room size |
|---|---|---|
| K-32324 | 5 kW | up to 84 cu ft |
| K-32325 | 7 kW | up to 112 cu ft |
| K-32326 | 9 kW | up to 240 cu ft |
| K-32327 | 11 kW | up to 317 cu ft |
| K-32328 | 13 kW | up to 447 cu ft |
| K-32329 | 15 kW | up to 500 cu ft |
Glass walls, windows and exterior walls
Large glass areas, windows and exterior walls lose more heat. Both manufacturers say they can call for a larger generator but give no exact percentage. If your room has them, the next size up is the safer choice.
Next steps
Every generator page lists the amps, breaker and wire size for each model, so your electrician can plan the 240V circuit. Shop complete steam shower kits, steam generators, or everything for a home steam room.
