How much material does planing remove?

A typical pass through a thicknesser removes 1.5–2mm from each face. To get flat, parallel faces from rough-sawn stock, expect to lose 2–3mm per face (4–6mm total thickness). Edge jointing typically removes 2–3mm per edge. Cupped or twisted boards lose more.

What do S1S, S2S, and S4S mean?

S1S = surfaced one side (one face planed flat). S2S = surfaced two sides (both faces planed parallel). S4S = surfaced four sides (both faces and both edges planed). Most furniture work requires S4S preparation.

Should I buy rough or pre-planed timber?

Rough-sawn timber is cheaper per board foot but requires a jointer and thicknesser to prepare. Pre-planed (PAR — Planed All Round) is convenient but costs more and limits your thickness options. For furniture making, rough-sawn gives you more control over final dimensions.

PAR stands for Planed All Round, meaning all four long faces are machine-planed smooth. PAR timber from UK merchants is surfaced to standard finished sizes: e.g. 44×69mm from nominal 50×75mm rough, or 44×94mm from 50×100mm rough.

WoodCalcs

Rough to Finished Calculator — Planing Allowances

Calculate finished timber dimensions from rough-sawn stock after surfacing and planing.

Rough Thickness

Material thickness

Rough Width

Shortest dimension of the area

Rough Length

Longest dimension of the area

Surfacing

Select the surfacing for your calculation

Removal per Face

Material removed from each face

Removal per Edge

Material removed from each edge

How We Calculate This

This calculator estimates finished dimensions from rough-sawn stock by subtracting material removal for planing and surfacing.

Material removal

Per face: Typically 2mm per face for reasonably flat stock (adjustable)
Per edge: Typically 3mm per edge for edge jointing (adjustable)
End trim: ~25mm total from both ends for squaring

Surfacing modes

S1S: Thickness loss = 1 × face removal
S2S: Thickness loss = 2 × face removal
S4S: Thickness loss = 2 × face removal, width loss = 2 × edge removal

Frequently Asked Questions

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Last updated: February 2026

All calculations are estimates. Always verify measurements and material quantities before cutting or purchasing.