Sauna Doors: Sizes, Glass and How to Choose

This guide covers the three kinds of sauna door, standard sizes and rough openings, glass, the rules every sauna door follows, and how a glass door changes the heater you need. Door specifications and prices are from our store as of October 1, 2026, and the installation rules come from sauna makers' instructions, listed at the end.

The three kinds of sauna door

All of them arrive prehung, already mounted in their jamb, so you set the whole unit into a framed opening.

Glass door or wood door?

• Glass doors make a small sauna feel bigger and let light in. PROSAUNAS suggests clear glass for an open, light feel and tinted glass for a softer, more private one. They are also the lowest-priced option.
• Wood doors with a window hold heat better. The PROSAUNAS Douglas Fir door has a dual-pane, argon-filled window, which the maker says reduces heat transfer while still letting in natural light. The solid door also gives more privacy.
• Frameless glass looks the most modern. Bathology's Elements 310 comes in bronze-tinted glass for an all-glass look with some shade for privacy.

Standard sizes and rough openings

A door's name is its nominal size. The rough opening, the hole you frame in the wall, has to be bigger to fit the jamb. Always frame to the maker's rough opening for the exact door you buy, and wait until you have the door to cut the hole.

Finnleo's building instructions give the same rule of thumb: frame a wood door's opening 2 inches wider and 2 inches taller than the door, and an all-glass door's opening 3-1/2 inches wider and 2 inches taller.

Which height? Full-height doors are 80 or 81 inches; shorter 70 to 73 inch doors fit lower walls. Finnleo says an 80-inch door typically has no threshold, while a 72-inch door may use one. Our 24 x 73 glass door comes with a threshold built in.

Which width? 24 inches is the standard. Finlandia Sauna recommends staying at 24 inches to limit heat loss and warping. Choose 30 or 36 inches when you need the room: a 36-inch door gives the wider opening used for wheelchair access.

The rules every sauna door follows

• It opens outward. Finnleo says sauna doors must always swing out, and HUUM's heater manual says the same. PROSAUNAS explains that an outward swing helps you get out quickly in an emergency.
• It has no lock. Finlandia says a sauna door should open out and have no lock. Sauna doors close with a roller catch or a magnet instead, so a push from inside always opens them. Every PROSAUNAS glass door uses an adjustable heavy-duty roller latch, and the Douglas Fir doors use self-closing hinges.
• The glass is tempered. The glass in our PROSAUNAS doors is 8 mm (5/16 inch) tempered safety glass, and the Elements 310 uses 5/16 inch safety glass.
• It doesn't open into a pool or spa room. Finlandia warns that chlorinated humidity rusts the hinges and warps the door.

The gap under the door is part of the ventilation

Most sauna doors deliberately stop short of the floor. The gap lets fresh air into the room. Our 81-inch glass doors and all the Douglas Fir doors leave a 3/4-inch air gap, and Bathology recommends up to an inch under the Elements 310.

The gap gets bigger in one common layout. If the sauna's exhaust vent goes into a washroom or shower room next door instead of outside, Harvia and HUUM both say the gap under the door must be at least 100 mm (about 4 inches). Plan the door and the vents together, following your heater's manual. Our DIY sauna guide covers vent placement.

A glass door means a bigger heater

Glass doesn't insulate like a wood wall, so the heater has to work harder. Heater makers account for this by counting glass as extra room volume:

Here's what that means for a real door. The glass in our 24 x 81 glass door measures about 24-7/16 by 80-1/8 inches, roughly 13.6 square feet. By HUUM's rule, that counts as about 45 extra cubic feet of room. In a 6 x 6 foot sauna with a 7-foot ceiling (252 cubic feet), that's like heating an 18% bigger room. The 24-inch Douglas Fir door's smaller window, about 7.5 square feet, adds about 25 cubic feet.

Our sauna heater size calculator asks about glass and does this math for you.

Hinges, handles and hardware

• Hinge side: every door we sell comes in a left- or right-hinge version. Check the maker's drawing for which side it calls left and right before you order. The PROSAUNAS glass doors also have reversible hinges that adjust 3 mm in four directions for fine-tuning.
• Hinges: the 24-inch glass doors have two aluminum hinges, silver or black to match the frame. The 36-inch glass doors have three stainless steel hinges.
• Handles: PROSAUNAS doors have a stainless steel pull outside and a wooden handle inside, because the inside handle sits in the heat. Finnleo suggests mounting handles with their center about 36 inches off the floor.
• Frame wood: PROSAUNAS glass doors come with an aspen frame (natural), a black alder frame or a thermally modified aspen frame. The Douglas Fir doors hang on a hemlock jamb.
• Door sensor: if you'll start your heater from a phone app, a door sensor tells the control whether the door is closed. The HUUM UKU door sensor is $82. Harvia's remote start, for example, has to be re-armed every time the door is opened.

Which sauna door should you buy?

• Most indoor saunas: the PROSAUNAS 24 x 81 glass door, $798.15. Full height, no threshold, a 3/4-inch air gap and a choice of three frame woods and clear or grey glass.
• Lower ceilings or a basement: the PROSAUNAS 24 x 73 glass door, $759.05, with its built-in threshold.
• Best heat retention: the PROSAUNAS Douglas Fir door with its insulated window, from $1,309. If it will face the weather, PROSAUNAS says it needs treatment for exterior use.
• Wheelchair access: a 36-inch door, either the glass door at $998.75 or the Douglas Fir door at $1,615.
• The most modern look: the Bathology Elements 310 frameless bronze glass door, from $1,086.97.

Browse every sauna door, or start with our step-by-step DIY sauna guide.