Short answer: the FD-3 is a 4-person full-spectrum infrared cabin that reaches 170°F and costs $6,495. It is the hottest and largest infrared cabin on this site. It needs a dedicated 240V circuit, which most infrared cabins don’t.
Why does an infrared sauna need 240V?
The heaters total 3,150W. On a 120V circuit that would be about 26A, more than a household outlet can supply. On 240V it is about 13.1A, which is why the listing calls for a dedicated 240V, 15A, single-phase circuit. An electrician has to install it.
That is a lighter job than a traditional sauna’s 30A or 40A circuit, but it is still a cost. Get a quote first.
At full power the cabin uses 3.15 kWh per hour, about $0.58 at the 2026 US average of 18.34 cents per kWh.
Will four people fit?
The interior is 67” wide and 41” deep, about 19 sq ft. A 67” bench gives four adults under 17” each. That is tight. I’d call it a comfortable sauna for two or three, and a four-person sauna when everyone is friendly.
The exterior is 72” x 46” x 78”, about 23 sq ft. It weighs 488 lbs, and 536 lbs shipped. Plan the delivery path and have help ready.
What does full-spectrum mean here?
The cabin combines long-wave carbon panels with short-wave Spectrum Plus panels, which the listing says are UL listed. The 170°F maximum is higher than the 140-150°F typical of carbon-only cabins. If you want infrared that feels closer to a traditional sauna’s heat, this is the reason to pay more.
What the listing leaves out
The listing says a limited warranty is included but not how long it lasts. Finnmark’s FD-5 is listed elsewhere with 10 years on the cabin. Ask the dealer whether the FD-3 gets the same, in writing.
You get, you give up
You get a cedar interior, a touchscreen controller, Bluetooth audio, and an 8mm glass door. You give up plug-in simplicity.
How it compares
The Finnmark FD-4 Trinity adds a traditional stove and runs on 120V, but seats 2 and costs $7,795. See Infrared Sauna Power: Outlet, 20A Circuit, or 240V?.
