About

Material procurement and inventory management often rely on weight-based pricing, yet fabrication requires precise linear dimensions. Engineers, machinists, and purchasing agents frequently encounter scenarios where a specific mass of raw material exists, but the usable length remains unknown. Estimating this incorrectly leads to material shortages or costly scrap. This calculator solves the mass-to-length conversion problem by utilizing material density and cross-sectional geometry.

Precision is vital when dealing with expensive alloys like Titanium or Inconel. A deviation in density values or geometric calculation can result in significant financial variance. This tool applies standard industrial densities and geometric formulas for rounds, squares, hexagons, and flat bars. It handles the unit conversion logic internally, allowing inputs in mixed units (e.g., metric diameter with imperial weight) to suit international supply chains.

Formulas

The core principle of the calculation derives length from the volume formula V = A × L and the density formula ρ = m ÷ V. By combining these, we isolate the length L.

L = mA × ρ

Where m is mass (weight), ρ is material density, and A is the cross-sectional area based on the profile shape.

Area Formulas by Shape:

Round Bar (Diameter d):
A = π ⋅ d²4
Square Bar (Side s):
A = s²
Hexagonal Bar (Width Across Flats w):
A = √32 ⋅ w²
Flat Bar / Sheet (Width w, Thickness t):
A = w × t

Reference Data

Material Grade	Density (kg/m³)	Density (lbs/in³)	Common Use Case
Mild Steel (1018)	7850	0.2836	Structural components, general fabrication
Stainless Steel 304	7900	0.2854	Kitchen equipment, piping, corrosion resistance
Stainless Steel 316	7980	0.2883	Marine environments, chemical processing
Aluminum 6061	2700	0.0975	Aerospace, automotive frames, bike parts
Aluminum 7075	2810	0.1015	High-stress aircraft structures
Copper (Pure)	8960	0.3237	Electrical wiring, heat exchangers
Brass (C360)	8490	0.3067	Fittings, musical instruments, hardware
Titanium Grade 2	4510	0.1629	Medical devices, chemical processing
Titanium Grade 5	4430	0.1601	Turbine blades, aerospace fasteners
Inconel 625	8440	0.3050	Jet engine exhaust systems
Tool Steel D2	7700	0.2782	Dies, punches, cutting tools
Cast Iron (Grey)	7150	0.2583	Engine blocks, machine bases
Gold	19320	0.6980	Electronics, jewelry
Lead	11340	0.4097	Radiation shielding, batteries
Zinc	7140	0.2580	Die casting, galvanizing

Frequently Asked Questions

Material grade significantly changes density. For example, Aluminum 7075 is denser (2810 kg/m³) than Aluminum 6061 (2700 kg/m³). For a 100kg block, 7075 would yield a shorter length than 6061. Always check the specific alloy grade, not just the base metal.

Hex bars are measured "Across Flats" (the flat-to-flat distance), not "Across Corners". The geometric area formula derived from the width across flats is approximately 0.866 multiplied by the square of the width. Using a simple square or circle formula will result in incorrect volume estimations.

No. This tool assumes perfect geometric shapes (ideal cylinders, prisms, etc.). Real-world rolled metals have corner radii (on squares/flats) or ovality tolerances (on rounds) that slightly reduce the actual cross-sectional area. For high-precision mass calculation, apply a safety margin of 1-2%.

This specific configuration calculates solid profiles. For tubes or pipes (hollow centers), you must subtract the area of the inner hole from the outer area. Using the "Round" setting here for a pipe will result in a massive underestimation of length because it assumes the shape is solid metal.