Calculator formulas
- Plywood & sheet material calculator — reviewed 4 September 2026Rectangular orientation grid: ceiling(surface length ÷ sheet length) × ceiling(surface width ÷ sheet width), compared with the rotated orientation when allowed. Planned sheets apply the entered allowance and round upwards. Weight uses sheet area × thickness × the density entered by the user.
- Timber length, volume and cost calculator — reviewed 4 September 2026Usable stock length = stock length − two end trims. Equal pieces per stock = floor((usable stock + kerf) ÷ (piece length + kerf)). Stock quantity is the larger of the equal-piece fit requirement and the entered percentage allowance. Purchased volume uses the gross purchased length × entered width × entered thickness.
- Linear metre and stock length calculator — reviewed 4 September 2026Net running metres = piece length × quantity ÷ 1000. Usable stock removes trim at both ends, and equal-piece fit allows the entered kerf between adjacent pieces. Stock quantity is the larger of the fit requirement and the entered percentage allowance.
- Mitre angle calculator — reviewed 4 September 2026For two equal flat pieces forming an inside corner C, the saw adjustment from square = (180° − C) ÷ 2 and the cut line from the long edge = C ÷ 2. A regular n-sided frame uses a saw adjustment of 180° ÷ n and an inside corner of 180° − 360° ÷ n.
- Sheet cut list optimiser — reviewed 4 September 2026Rectangular parts are sorted by area and placed into a repeatable first-fit sheet layout. Edge trim reduces usable stock and the entered kerf separates adjacent parts. The result is one workable arrangement, not proof that no tighter layout exists.
- Compound mitre calculator for cornice — reviewed 4 September 2026For sprung cornice or crown moulding laid flat, with included wall corner C and spring angle S: mitre angle = atan(sin(S) ÷ tan(C ÷ 2)); bevel angle = asin(cos(S) × cos(C ÷ 2)). Zero means a square table setting or vertical blade. Direction, reference face and waste side remain machine- and joint-specific. As checks, a 90° corner with a 38° spring angle gives a 31.62° mitre and 33.86° bevel; with a 45° spring angle it gives a 35.26° mitre and 30.00° bevel.
- Shelf spacing calculator — reviewed 4 September 2026For N loose shelves of thickness t inside height H, equal clear opening = (H − N×t) ÷ (N+1). Shelf underside i = i×opening + (i−1)×t. Optional 32 mm marks round each exact underside independently from the entered first-hole height and report how far the shelf would move.
- Inset drawer front spacing calculator — reviewed 4 September 2026Equal inset front height = (opening height − top reveal − bottom reveal − (N−1)×gap between fronts) ÷ N. Width subtracts the two side reveals. Top, centre and bottom marks accumulate from the same unrounded front height.
External woodworking context
- Health and Safety Executive — accessed 4 September 2026Circular saw bench (rip saw). Used only for machine-safety context around circular-saw bench work.
- Health and Safety Executive — accessed 4 September 2026Working with woodcutting machinery. Used for the point that a layout calculator does not replace guarding, training or a safe system of work.
- Health and Safety Executive — accessed 4 September 2026Wood dust. Used for general workshop context; this site does not calculate exposure.
- J. E. Jansson — accessed 4 September 2026Compound Miter Saw Calculator. Used for the stated saw-angle definitions: bevel as blade tilt from vertical and mitre as table angle from a square cross-cut. The calculator here is deliberately narrower and covers sprung moulding laid flat.
- DeWalt — accessed 4 September 2026DCS781 instruction manual. Used only to support the point that crown-moulding orientation, bevel direction, clamping and clearance checks depend on the machine instructions.
Values that must come from the job
The site does not publish one universal plywood density, blade kerf, merchant stock size, timber strength, span, moisture, cost or waste percentage. Those values vary. Use the current supplier specification, your measured cut and the requirements of the actual job.