Wood & Woodworking calculators

Calculators for sawyers, woodworkers, and firewood cutters: lumber volume, log scaling rules, firewood heat content, seasonal wood movement, and CNC feeds. Built around how wood behaves in a real shop, not just the textbook.

• Board Foot CalculatorBoard feet = thickness (in) × width (in) × length (ft) ÷ 12, multiplied by the number of pieces.
• CNC Feeds and Speeds Calculator (Chip Load)Feed rate = spindle RPM × number of flutes × chip load per tooth, and surface speed = π × tool diameter × RPM.
• Compound Miter Angle CalculatorFor n sides leaning a degrees from vertical, set the blade bevel to arcsin(cos a × sin(180° ÷ n)) and the miter to arctan(sin a × tan(180° ÷ n)).
• Equilibrium Moisture Content Calculator (Wood EMC)Wood settles at a moisture content set by the air around it: about 9% at 70°F and 50% relative humidity, and about 12% at 65% humidity.
• Firewood BTU Calculator by SpeciesA cord of seasoned white oak holds roughly 28 million BTU of usable heat, about 70% more than a cord of quaking aspen; species and moisture drive the difference.
• Firewood Cord and Face Cord CalculatorA full cord is 128 cubic feet of tightly stacked wood (4 ft × 4 ft × 8 ft); a face cord is one 4 ft × 8 ft face at whatever log length you cut.
• Log Scale Calculator (Doyle and International 1/4")Enter the small-end diameter inside bark and the log length to compare Doyle and International 1/4-inch board-foot estimates.
• Segmented Bowl Ring CalculatorEach segment end is cut at 180° ÷ n, and the outside length of a segment is the ring diameter times tan(180° ÷ n) across the flats or sin(180° ÷ n) across the corners.
• Shelf Sag Calculator (Bookshelf Deflection)A shelf on two supports sags 5wL⁴ ÷ (384EI) at its middle, so doubling the span makes it sag 16 times as much, while doubling the thickness cuts it to one-eighth.
• Wood Movement Calculator (Shrinkage and Expansion)A 12-inch flatsawn white oak board changes about 0.17 inch in width for every 4 percentage points of moisture change.