Methodology & accuracy
Engineering accuracy comes before appearance. This page explains where the data comes from, how each calculation is checked, and what the tools do not do.
1. Section data
European I and H sections (IPE, HEA, HEB, HEM) are taken from published stockholder data sheets that tabulate EN 10365:2017 dimensions and properties. Each value is stored exactly as published, with its standard, edition and source. On every build the platform recomputes area, mass, Iy, Iz and Wpl,y from the dimensions (h, b, tw, tf, r) using exact geometry including the root radii. If any of 90 rows differs from its published value by more than 1 %, the build fails and nothing is published. Current worst-case agreement is under 0.3 % (mass rounding).
Hollow sections (CHS, SHS, RHS) are computed from nominal dimensions. For hot-finished sections the outer and inner corner radii are taken as 1.5t and 1.0t (EN 10210-2); cold-formed sections use the thickness bands of EN 10219-2. These records are marked computed geometry; size availability must be confirmed with a supplier.
2. Calculation engine
Calculations run on the SteelNomic server. Your browser sends the inputs; the server validates every value against the calculator's declared limits, performs the calculation and returns the results with formulas, assumptions and warnings. Each calculator has a version number; any change to a formula or to the data increments it and is recorded in the changelog.
3. Testing before release
- Benchmark cases with independent hand calculations for every calculator (for example: single-V butt weld t = 16, g = 3, c = 2, α = 60° → 161.2 mm² groove; CHS 168.3 × 6.0 → 24.02 kg/m; welded I 600×250×10/20 → Iy = 98 768 cm⁴).
- Rejection tests: unknown inputs, wrong types, out-of-range values and geometrically impossible shapes are refused with a clear message.
- Consistency tests on the section database: identity, ordering, dimensional sanity, W = I / (h/2) and i = √(I/A).
4. What the tools do not do
SteelNomic calculators produce preliminary quantities and geometric properties. They do not check member resistance, stability, weld or bolt strength, fatigue, fire resistance or code compliance, and they do not replace drawings, specifications, manufacturer data or approval by a qualified engineer. Rolling tolerances, mill under/overweight and fabrication allowances are not included unless stated.
5. Units and conventions
SI units throughout: mm for dimensions, kg and t for mass, m² for surfaces, cm² / cm⁴ / cm³ for section properties as in European tables. Default steel density is 7850 kg/m³, the nominal value used by EN mass tables; it can be changed in each calculator.
6. Corrections
If you find an error, please report it with the page, inputs and the value you expected. Confirmed corrections are published in the changelog with the affected version.