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Reinforced Concrete Tied Column Axial Capacity Calculator (ACI 318)

Estimate the maximum nominal axial load capacity of a tied (non-spiral) reinforced concrete column.

Computed in your browser — nothing you enter is uploaded. Figures are presented for United States against IRC 2024, and every formula is cited under regulatory standards below.

Last verified 2026-08-26 · v1.0.0

Market
Imperial · sales tax

Maximum nominal axial capacity

4314.24 kN

Check your inputs

This is the maximum NOMINAL capacity (already including the 0.80 tied-column reduction for accidental eccentricity) — a design must still apply the strength reduction factor (φ, typically 0.65 for tied columns) and verify slenderness effects, both outside this calculator's scope.

Reinforcement ratio
2.5 %

At the values currently entered, the maximum nominal axial capacity works out to 4314 kN. Note that longitudinal steel area (ast) sits at the low end of the range this calculator was checked against, so treat the output as indicative rather than settled. Confidence is moderate: the method is sound, but real materials and site conditions vary. Figures are shown for United States, where IRC 2024 is the governing residential reference; switch the market above if you are building elsewhere.

Add the equipment this sizes

This result is a specification — 4,314.24 kN — not a quantity. Put the thing it sizes into your project: how many, what you call it, and your supplier’s price.

Preliminary estimate, not certified engineering. This tool produces an indicative quantity calculation for planning purposes only — it is not a certified structural analysis, a guaranteed material takeoff, or a substitute for building department approval. Always verify measurements on-site and have a licensed contractor or structural engineer review any load-bearing, code-sensitive, or safety-critical work before purchasing materials or starting construction. Spotted an arithmetic or standards error? Report it to contact@craftquantities.com with your inputs — confirmed fixes become pinned regression tests.

[Schema Verified] Computed in alignment with American Concrete Institute (ACI 318-19) formulas and International Residential Code (IRC 2024) spatial boundaries.

Regulatory standards & verification citations

  • ACI 318 maximum nominal axial capacity for tied columns: Pn(max) = 0.80 x [0.85 x f'c x (Ag - Ast) + fy x Ast]

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Frequently asked questions

Why is there a 0.80 factor even before the strength reduction factor?
ACI 318 applies this factor specifically to tied columns to account for unavoidable accidental eccentricity in real construction — spiral (helically-reinforced) columns get a less severe 0.85 factor instead, reflecting their more ductile, confined behavior.
What reinforcement ratio range does ACI 318 require?
Between 1% and 8% of gross cross-sectional area — below 1% risks brittle failure and creep-related overstress of the steel; above 8% causes severe rebar congestion that makes proper concrete placement and consolidation very difficult.
Does this account for slenderness (buckling)?
No — slender columns (tall relative to their cross-section) need a separate moment magnification check per ACI 318 Chapter 6, which can significantly reduce usable capacity below this short-column value.