Work out slab load instantly with clear inputs, formula shown and shareable results.
Slab dead load starts with its own weight, thickness in metres times 25 kN/m³ for reinforced concrete, then adds screed, finishes and services. Live load comes from the occupancy schedule. The factored total drives design, and for a simply supported one-way slab the moment per metre width is wL²/8.
Dead load
kPa = thickness m x 25 + finishes and services
Design moment
M = 1.2 dead + 1.6 live, then w L² / 8 per metre width
Preliminary estimate only. Slab loads, spans and reinforcement must be designed by a qualified structural engineer to the applicable code.
kPa = thickness m x 25 + finishes and services. Slab dead load starts with its own weight, thickness in metres times 25 kN/m³ for reinforced concrete, then adds screed, finishes and services.
Plain concrete is about 24 kN/m³ and reinforcement raises it to roughly 25. Codes specify 25 for normal weight reinforced concrete so the figure is consistent between designers.
This calculator takes 4 inputs: Slab thickness, Finishes and services, Live load, Effective span. The pre-filled defaults are a realistic worked example — replace them with your own site or project figures.