About this section weight calculator
Section weight calculator
Section Weight Calculator with Custom Drawing and DXF Import
Draw a section profile or select a rectangle, hollow section, circle, pipe, I section, channel, or angle; then calculate volume and weight per unit length from material density in metric or imperial units.
Use this section weight calculator to calculate net cross-sectional area, volume and material weight from a standard profile, a custom sketch or a 2D DXF profile. It supports carbon steel, stainless steel, aluminium, cast iron, copper, brass, titanium, HDPE and user-defined material density in metric and imperial units.
Common engineering uses
Common engineering uses
- Estimate kg/m, lb/ft or another mass-per-length basis for plate, flat bar, round bar, pipe, RHS, I sections, channels and angles.
- Draw a custom closed section from straight lines, rectangles and circles, then apply exact coordinates, segment lengths, angles, chamfers and convex-corner fillet radii.
- Import a CAD cross-section exported as DXF and calculate its net material area and member weight without manually recreating every dimension.
Outputs to review
Outputs to review
- Net section area after nested openings are subtracted from outer profiles.
- Material volume and weight per metre, foot or inch in kilograms or pounds.
- Optional total volume and total member weight from an entered extrusion length.
How to use this tool
How to use this tool
- Choose metric or imperial units and select steel, aluminium, stainless steel, another common material, or enter a custom density.
- Select a predefined section profile, draw closed straight-line, rectangle or circle profiles, or upload a closed 2D DXF.
- Enter exact profile dimensions and apply chamfers or fillet radii to convex custom corners where required.
- Review net area, volume and mass per selected unit length; optionally enter total member length for total weight.
How to use the result
Choose the input unit system and material, then select a predefined profile or build a custom closed sketch. For DXF import, export planar closed polylines, connected closed lines or circles and confirm the drawing unit. Review geometry warnings before using the mass value, and compare standard rolled or extruded products with current supplier mass tables because corner radii and production tolerances can change the catalogue weight.
Assumptions, limitations, and formulas
Assumptions
The section is treated as a constant cross-section extruded along a straight member length.
Nested closed profiles are interpreted by even-odd containment: outer loops add material and enclosed loops subtract openings.
Material densities are representative values; user-defined density should be used when the specified alloy, temper, grade, porosity, or product data differs.
Limitations
DXF import supports planar closed LWPOLYLINE/POLYLINE entities, connected LINE loops, CIRCLE entities, and polyline bulge arcs; unsupported or open profiles are not included.
Overlapping closed bodies are rejected because profile union or subtraction cannot be inferred safely without an explicit CAD region operation.
Nominal I and channel presets use sharp corners; import or draw exact geometry when root radii and manufacturer tolerances materially affect the result.
Calculated mass is a geometry and density estimate and should be checked against current product standards, supplier mass tables, and actual manufacturing tolerances.
Formula notes
Net cross-sectional area is the sum of outer closed-loop areas minus nested opening areas.
Volume = net cross-sectional area × member length.
Mass = volume × material density; kg/m and lb/ft are converted from the same SI area and density basis.
Common questions
How is section weight per metre calculated?
The calculator finds the net cross-sectional area, multiplies that area by one metre of member length to obtain volume, and multiplies the volume by the selected material density. The same physical result is converted for pounds per foot or other selected output units.
Can a hollow or multi-hole section be calculated?
Yes. Draw or import the outer closed profile and each enclosed hole as its own closed profile. Nested loops are treated as openings using even-odd containment and are subtracted from the material area.
What DXF geometry can be imported?
This release imports planar closed LWPOLYLINE and POLYLINE entities, connected LINE loops, CIRCLE entities and polyline bulge arcs. Open profiles and unsupported CAD entities are ignored with a warning or rejected when no valid closed profile remains.
Why can calculated section weight differ from a supplier table?
Supplier masses can include standard root radii, corner radii, extrusion geometry and permitted dimensional or mass tolerances that are not present in a simplified sharp-corner profile. Use exact DXF geometry or the supplier's current published mass for procurement and final design.