Structural Load Calculator
LRFD factored load combinations per ASCE 7. Enter unit loads in psf and tributary area in ft².
ASCE 7 LRFD load combinations (Section 2.3.1)+
U = max[ 1.4D ; 1.2D + 1.6L + 0.5(Lr or S) ; 1.2D + 1.6(Lr or S) + (L or 0.5W) ; 1.2D + 1.0W + L + 0.5(Lr or S) ; 0.9D + 1.0W ]
D dead, L live, Lr roof live, S snow, W wind. Seismic (E) and rain (R) are omitted for clarity.
Sizing aid only. Full design requires load path checks, lateral system, drift, foundation, connections, and stamped drawings by a licensed Structural P.E. or S.E.
Frequently asked questions
What load combinations does this use?+
LRFD per ASCE 7-22 Section 2.3: 1.4D, 1.2D+1.6L+0.5(Lr/S), 1.2D+1.6(Lr/S)+(L or 0.5W), 1.2D+1.0W+L+0.5(Lr/S), 0.9D+1.0W. The maximum of all combinations is reported.
Where do I get the snow and wind loads?+
Snow: ASCE 7 Ch. 7, function of ground snow pg, exposure, thermal, importance. Wind: ASCE 7 Ch. 26-30, function of basic wind speed V, exposure, MWFRS vs C&C, and gust factor. Use ATC Hazards by Location for site-specific values.
Is this for the whole structure or one member?+
One tributary area. Enter the area carried by the member (beam, joist, column) and the unit loads. Total factored load is reported in psf and total kip.
What is tributary area?+
The portion of floor or roof that delivers load to the member. For an interior beam, it's the beam length × half the distance to each adjacent beam.
Do you handle seismic?+
No. Seismic (E) load combinations and the equivalent lateral force procedure are outside scope. A licensed S.E. should run those in design software.
Why is dead load 'D' so big when I add roofing and MEP?+
Real buildings carry 15-30 psf in finishes, MEP, ceiling, and partitions on top of structural self-weight. Don't underestimate D — it shows up in every combination.