Column Load Capacity Calculator
Estimate the axial load capacity of a reinforced concrete column using the ACI 318 simplified formula.
Column Parameters
Units:
Width × depth for rectangular; π·r² for circular.
ACI 318 limits: 1% – 8% of gross area.
Enter column parameters and click Calculate.
Nominal Capacity
—
kips
Pn (unfactored)
Design Capacity
—
kips
φPn (factored)
Check Against Factored Demand (Pu)
kips
Calculation Breakdown
Preliminary design only. All structural members must be reviewed by a licensed engineer before construction. Slenderness, biaxial bending, and seismic effects are not included.
Summary
Estimate the axial load capacity of a reinforced concrete column using the ACI 318 simplified formula.
How it works
- Enter the column gross cross-sectional area (width × depth for rectangular, or π·r² for circular).
- Enter the longitudinal steel ratio ρg as a percentage (ACI 318 limits: 1%–8%).
- Enter the concrete compressive strength f'c (typically 3000–6000 psi or 21–41 MPa).
- Enter the steel yield strength fy (typically 60 ksi / 414 MPa for Grade 60 rebar).
- Select the column tie type: tied (φ = 0.65) or spiral (φ = 0.75).
- The calculator applies ACI 318 §22.4.2: φPn = φ · 0.80 (or 0.85) · [0.85·f'c·(Ag − Ast) + fy·Ast].
Use cases
- Quick preliminary check of a new RC column cross-section.
- Comparing tied vs. spiral column efficiency for a given load demand.
- Educational demonstration of ACI 318 axial-load provisions.
- Verifying hand calculations before full detailed design.
- Estimating capacity for lightly loaded columns in low-rise buildings.
- Sensitivity analysis: seeing how f'c or ρg changes affect capacity.
Frequently Asked Questions
Last updated: 2026-06-13 ·
Reviewed by Nham Vu