Estimate the finished width of a panel assembled from equal-width boards. Enter actual board width before edge preparation, the amount removed from each of both long edges of every board, and the total final trimming across the panel width. All length inputs and results use metres: 100 mm = 0.100 m and 1 mm = 0.001 m.
Use a whole board count from 1 to 1000, board width from 0.001 to 2 m, removal per edge from 0 to 0.1 m, and total final trimming from 0 to 2 m. Length inputs use increments of 0.0001 m (0.1 mm). These are calculator entry limits, not recommended machining allowances.
A physically valid panel also requires twice the edge removal to be less than the starting board width, and total final trimming to be less than the combined prepared-board width. Check these conditions yourself: the arithmetic calculator does not enforce comparisons between inputs. A zero or negative finished width means the allowances leave no usable panel; it is not a valid finished dimension. Fractional board counts are invalid even if accepted by an input control.
Final trimming is the sum removed from the two outside sides after assembly. For 5 mm removed from each side, enter 0.010 m. Trimming the panel ends changes its length and must not be entered here. Include all width consumed by final cuts in your trimming allowance.
This formula is derived directly from width accounting under the stated assumptions: removing e from both edges leaves w − 2e per board. Multiply by n boards and subtract the combined final trim T. The lost width is the original combined width minus the finished width, giving 2ne + T.
The algebraic expansion uses the distributive property described in OpenStax, Prealgebra 2e, section 7.3. That source supports the algebra; the panel formula is the derivation shown here, not a woodworking performance formula.
| Boards | Width per board | Removal per edge | Total final trim | Calculation of finished width | Total width lost |
|---|---|---|---|---|---|
| 5 | 0.1000 | 0.0010 | 0.0100 | 5 × (0.1000 − 2 × 0.0010) − 0.0100 = 0.4800 | 0.0200 |
| 4 | 0.1500 | 0.0020 | 0.0060 | 4 × (0.1500 − 2 × 0.0020) − 0.0060 = 0.5780 | 0.0220 |
| 3 | 0.1200 | 0 | 0 | 3 × 0.1200 = 0.3600 | 0 |
The model assumes equal starting board widths and the same removal from both long edges of every board, including the two outermost edges of the assembly. It assumes edge-to-edge assembly without overlaps and treats glue-line thickness as zero. It does not account for gaps, moisture movement, clamping deformation or later width changes.
If your measurements already describe prepared boards, enter zero edge removal to avoid subtracting it twice. For unequal board widths or unequal edge allowances, this calculator’s uniform-board model does not directly represent the job.
Total width lost is a linear dimension, not waste volume or a waste percentage. This calculator does not predict adhesive bond strength or assess joint quality.
Formula source
A registered thumbnail asset was not supplied. Create and register a 400 × 400 pixel WebP thumbnail before activation, then reference its real asset ID in the first image block. Match neighboring thumbnails: a cute yellow five-point star mascot with a cheerful face and hands, floating without separate legs or feet, on a white background with playful navy, blue and teal graphics. Suggested scene: the mascot measuring adjacent wood boards, with edge-removal strips and the finished panel width illustrated.