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Masonry Lintel Uniform Load Capacity Calculator

Compute the maximum uniform load a lintel of known allowable moment capacity can safely carry over a given span.

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
4.92 ft
Schematic, drawn to the proportions you entered — not to scale on screen.

Maximum allowable uniform load

53.33 kN/m

Check your inputs

This checks bending moment capacity only — the lintel must also satisfy shear capacity and deflection limits, both outside this calculator's scope, and this assumes a simple uniform load with no point loads or eccentricity.

For the dimensions entered, expect a maximum allowable uniform load of 53.3 kN/m. Moderate confidence — sound arithmetic, but allow for the variation any real site introduces. Set for United States against IRC 2024. The market selector changes both the units and the code cited.

Add the equipment this sizes

This result is a specification — 53.333 kN/m — 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

  • Simply-supported beam under uniform load: maximum moment Mmax = wL²/8; rearranged to solve for allowable uniform load: w(max) = 8 x Mallow / L²

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Frequently asked questions

Where does 'allowable moment capacity' come from?
It's typically published in a manufacturer's precast or steel lintel load table, or calculated directly for a reinforced masonry or concrete lintel from its reinforcement and section properties.
Why does span have such a large effect on capacity?
Because span appears squared in the formula — doubling the span cuts the allowable uniform load to a quarter, which is why even modestly wider openings often need a noticeably stronger (or deeper) lintel.
Does this account for the lintel's own self-weight?
No — this calculates the maximum ADDITIONAL uniform load the lintel can carry given its moment capacity; if the lintel's self-weight is a meaningful fraction of the total, subtract it from the wall/floor load above before comparing to this capacity.