Load Combinations Calculator

Combines a permanent action and up to two variable actions into ULS and SLS design values, per BS EN 1990 and its UK National Annex. Use the ULS result as N_Ed, UDL, point load, or V_Ed in the other modules.

Permanent action Characteristic value, G_k

Any consistent unit - kN, kN/m, kN/m²

Leading variable action Characteristic value, Q_k,1 Category

Accompanying variable action (optional - leave at 0 if there isn't one) Characteristic value, Q_k,2 Category

Standards used on this page:

BS EN 1990:2002+A1:2005 (Basis of structural design) — Equation 6.10 (ULS), §6.5.3 (SLS combinations)
UK National Annex to BS EN 1990 — Table NA.A1.1 (combination factors), Table NA.A1.2(B) (partial factors γ_G = 1.35, γ_Q = 1.5)

Accuracy & scope note:

Implements Equation 6.10 only — the UK NA also permits a potentially more economical two-equation approach (6.10a with the worse of 6.10b), which is not implemented here. Eq 6.10 alone is always safe, just occasionally less economical.
Assumes all actions are unfavourable and additive — the normal case for sizing a beam or column under gravity loads. Does not handle favourable actions, uplift, or overturning/stability checks.
Supports one permanent action and up to two variable actions only. More complex load cases (multiple permanent actions, three or more variable actions, accidental or seismic situations) are not covered.
Load values are unit-agnostic — this tool only performs the factor arithmetic. Keep units consistent across all inputs yourself.

This tool provides preliminary, indicative structural calculations only, intended to assist with initial sizing and understanding. It is not a substitute for assessment by a qualified structural engineer, and cad-steel.co.uk accepts no responsibility for its use in any final design. Always have load cases and combinations checked and confirmed by a competent engineer before construction.