Mr. Steam MS400R 9 kW Steam Generator vs Steamist SMP-7 SM Plus 7.5 kW Steam Generator
$3,360 against $1,645. Here is where the $1,715 difference actually goes.
Independent and reader-supported. We earn a commission if you buy through our links, at no extra cost to you. Rankings are never sold, and every figure says where it came from. Prices verified September 2026.Full disclosure
Mr. Steam
MS400R 9 kW Steam Generator
$3,360
8.4 / 10
Converting an existing tiled shower, or a new steam room up to about 250 cu ft
Higher lab score
Steamist
SMP-7 SM Plus 7.5 kW Steam Generator
$1,645
8.5 / 10
A tiled shower conversion up to 250 cu ft where price and a 40A circuit decide it
Specifications side by side
| Spec | Mr. Steam MS400R 9 kW Steam Generator | Steamist SMP-7 SM Plus 7.5 kW Steam Generator |
|---|---|---|
| Price | $3,360 | $1,645 |
| Lab score | 8.4 | 8.5 |
| Output | 9 kW, 240V single phase | 7.5 kW, 240V or 208V single phase |
| Room size | 162–257 adjusted cu ft | Up to 250 adjusted cu ft |
| Draw | 38 A on a 50A breaker | 31 A on a 40A breaker at 240V (36 A, 50A at 208V) |
| Controls | Sold separately (TouchTempo $700, Basic Butler package $1,278) | Sold separately (Steamist TSC series required) |
| Tank | Stainless steel, full-port drain valve | Stainless steel, optional auto drain |
| Size | 14.5 × 6.75 × 14.75 in, 25 lb | 15 × 6 × 15.5 in |
The verdict
Steamist SMP-7 SM Plus 7.5 kW Steam Generator takes the higher score here. The value pick for a converted shower: 7.5 kW covers rooms up to 250 cu ft on a 40A circuit, and at $1,645 it is about half the Mr. Steam's dealer price. Every figure is Steamist's own rating chart; we have not metered a session or timed a warm-up. Budget a TSC control on top.
It is also the cheaper of the two by $1,715, which makes this an unusually easy call. The case for the Mr. Steam MS400R 9 kW Steam Generator rests on what it does differently, not on value: The residential steam generator dealers stock most widely, sized for a 162–257 cu ft tiled enclosure. Every figure here is Mr. Steam's nameplate as published by its dealers; we have not metered a session or timed a warm-up. Budget the control and steam head on top, and a 50A circuit.
Put plainly — unless one of the MS400R 9 kW Steam Generator's specific strengths below is the thing you are buying for, take the SMP-7 SM Plus 7.5 kW Steam Generator and put the $1,715 toward installation, which is the line item most first-time buyers underestimate.
What each one is good at
Mr. Steam MS400R 9 kW Steam Generator
Strengths
- Stainless tank, serviceable copper element and a lifetime limited warranty on the unit, per dealer listings
- Mounts up to 25 ft from the enclosure in a closet, vanity or attic, so the bathroom stays quiet
- Assembled in Long Island City, NY, with parts and controls available from the same dealers that sell the heaters
Compromises
- Bare unit: a control and steam head add $700–$1,278 before it runs
- Needs a 240V 50A dedicated circuit, a water line and a drain, plus a fully tiled, vapor-barriered enclosure
- Warm-up, kWh per session and enclosure temperature are all manufacturer claims until we bench it
Steamist SMP-7 SM Plus 7.5 kW Steam Generator
Strengths
- Lowest verified price of any residential generator we have looked at, from an authorized dealer
- 31 A on a 40A breaker at 240V, one size smaller than the 9 kW Mr. Steam's circuit
- Stainless tank, proportional heating and a limited lifetime warranty, per Steamist
Compromises
- Runs only with a Steamist TSC control, sold separately; the unit does nothing without one
- Tops out at 250 cu ft, so a large or high-ceilinged room needs the SMP-10
- Warm-up, kWh per session and enclosure temperature are all manufacturer claims until we bench it
Prices captured September 2026 from manufacturer and retailer pages and subject to frequent promotion. Confirm before buying. See our testing method for how lab scores are assigned.