Sheet Metal Calculators

These tools turn measured press-brake data into flat blanks and machine checks. The sheet-metal K-factor calculator back-solves K = (BA/theta - R)/t from measured bend allowance or a flat sample, then reports equivalent bend allowance, bend deduction, outside setback and neutral-axis offset. The sheet-metal bend allowance calculator computes the neutral-axis arc consumed by a bend, BA = (π/180)·A·(R + K·t), along with outside setback OSSB = (R + t)·tan(A/2) and bend deduction BD = 2·OSSB − BA, from the bend angle A, inside radius R, thickness t and the K-factor that locates the neutral axis. The press-brake bend deduction calculator then gives the flat (blank) length as the sum of the outside flanges minus one deduction per bend and includes a normalized bend deduction chart for common 90-degree setup checks.

For formed rectangular parts, the sheet metal box flat pattern calculator lays out an open tray or pan blank from outside mold-line base dimensions, side height, bend radius, thickness and K-factor. It returns flat blank length and width, bend-line offset from each edge, bend allowance, bend deduction and a simple corner-relief screen. For cone and duct-style developments, the sheet metal cone flat pattern calculator develops a cone or conical frustum into outer radius, inner radius, sector angle, slant height, arc lengths and blank area with seam allowance. The square to round transition calculator handles the separate rectangular-to-round layout problem with equal stations, true lengths, perimeter mismatch, max skew angle and seam-aware blank area. The duct transition calculator covers HVAC reducer airflow geometry from airflow, inlet/outlet size, taper limit and sheet thickness, returning velocity change, recommended transition length, controlling angle and a rough blank-area estimate. For machine capacity, the press brake tonnage calculator estimates air-bending force from thickness, bend length, V-die opening and tensile strength with F = 1.6·UTS·L·t²/V. That makes die opening, material strength and geometry visible instead of burying them in a chart. For finishing estimates, the powder coating coverage calculator turns developed surface area, dry-film thickness, powder SG, transfer efficiency and reclaim into pounds to plan, actual coverage and material cost.

They are for sheet-metal designers, fabricators and CNC programmers who need the blank, pattern, tonnage and finishing material to make sense before cutting a batch. See the guide on what the K-factor is, the difference between bend allowance and bend deduction, and the sheet-metal gauge chart to pull a thickness by material.