Cladding Board-Feet Calculator
Enter your room's dimensions, door opening, and board thickness to get the wall and ceiling surface area and the board feet of paneling to order, waste allowance included.
Cladding needed
Where the number comes from
The calculator first works out your gross surface area — the four walls (twice the sum of length and width, times height) plus the ceiling if you're cladding it too — then subtracts the door opening to get the net area you actually need to cover. A waste percentage is added on top for trimming, joints, and mistakes, and the result is multiplied by your board's nominal thickness to get board feet.
Most home sauna interiors use aspen, cedar, or thermally modified wood milled at 5/8in to 3/4in nominal thickness. Species and thickness both change the board-foot price at the yard, so it's worth pricing a couple of options once you have the quantity.
Frequently Asked Questions
What exactly is a board foot?
A board foot is a volume measurement, not an area one: one square foot of surface, one inch thick. It's the unit most lumber yards price by, because it lets them compare boards of different widths and lengths on equal footing. Covering more surface, or using thicker stock, both increase the board feet needed.
Why does the formula just multiply area by thickness?
Because a board foot is defined as 1 sq ft at 1 inch thick, covering an area A with nominal thickness T inches always takes A × T board feet — the width and length of the individual boards cancel out of the math entirely. It's a shortcut that happens to be exactly correct, not an approximation.
Why add a waste allowance?
Tongue-and-groove paneling loses some coverage to the interlocking joint, boards get trimmed to fit around corners and the door, and a few pieces are cut wrong or split. A 10% allowance is a common starting point; add more if your room has a lot of corners, a sloped ceiling, or few clear board lengths available.
Should I clad the ceiling the same as the walls?
Most home saunas clad the ceiling in the same wood for a consistent look and because the ceiling area near the heater gets just as hot as the walls. If you're leaving it exposed or using a different material, uncheck the ceiling option to price the walls alone.
Design and planning tool only. This is a material-quantity estimate for budgeting and ordering, not a cut list — confirm actual board lengths and layout with your supplier or installer before ordering.