Concrete Load Calculator
This concrete load calculator estimates what a slab-on-grade can carry: allowable interior point load and uniform load, computed with the Westergaard interior-load equations and PCA method from thickness, concrete strength and subgrade support — with every assumption stated.
Como usar esta calculadora
- Insira suas dimensões — pés para comprimentos, polegadas para a espessura.
- Ajuste as opções — porcentagem de desperdício, tamanho do saco e o preço local do concreto.
- Leia seus resultados — volume, sacos, peso e custo são atualizados ao vivo enquanto você digita.
A fórmula
MOR = 7.5√f'c ÷ SF 2.0; ℓ = [Et³/12(1−ν²)k]^0.25; P = σ_allow·2πt² ÷ [3(1+ν)(ln(ℓ/b)+0.6159)] Exemplo resolvido: A 4 in slab, 3,000 psi concrete on fair subgrade (k=100), 6 in load radius: allowable interior point load ≈ 5,000–6,000 lb — a loaded pickup wheel is fine; a loaded skid-steer may not be.
A slab capacity calculator has to respect where the load sits: these results are for interior loading, away from edges and joints. Edge and corner loads stress a slab roughly 1.5–2× more — keep heavy wheels off unsupported edges.
Thickness dominates: capacity scales roughly with t², so a 6-inch slab carries about 2.25× the point load of a 4-inch slab in the same conditions. Subgrade is next — a slab is only as strong as what's under it.
This concrete slab load calculator is an informational screening tool using unreinforced flexural capacity with a 2.0 safety factor. Reinforcement adds crack control and post-crack capacity but the uncracked estimate governs serviceability.
Perguntas frequentes
Perguntas comuns sobre a concrete load calculator.
How much weight can a 4 inch slab hold?
On decent subgrade with 3,000 psi concrete: interior point loads in the ~5,000 lb range per wheel/leg (with safety factor). Passenger vehicles are fine; concentrated racking or equipment legs need checking.
How much more can a 6 inch slab carry?
Point capacity scales with thickness squared: a 6 in slab carries roughly 2.25× a 4 in slab — typically 11,000+ lb interior point loads on good subgrade.
Why does subgrade matter so much?
The slab spreads load into the ground; soft subgrade lets the slab bend further, raising flexural stress. Doubling k (subgrade modulus) meaningfully raises capacity — compaction is cheap strength.
Can I use this for a suspended slab?
No — this tool models slab-on-grade only. Suspended/elevated slabs are structural members requiring engineered design.
Calculadoras relacionadas
Mais ferramentas da família de calculadoras de concreto.