Max One-Way Slab / Beam Span for a Given Depth (ACI 318-19)
The inverse of the minimum-thickness tile: with the slab or beam depth fixed, the longest span that still waives a deflection calculation, max_span = h x denom / (12 kfy klw). A 10 in both-ends-continuous Grade 60 member spans up to 23.3 ft without a deflection check; a longer span needs a deeper member or an explicit calculation. A design aid, not the engineer of record's stamped design.
Formula and source
max_span = available_thickness x denom / (12 x kfy x klw), the ACI 318-19 minimum-thickness relation hmin = 12 l / denom x kfy x klw solved for the span; denom = {simply:20, one-end:24, both-ends:28, cantilever:10}.
The ACI 318-19 Table 7.3.1.1 (one-way slabs) and Table 9.3.1.1 (beams) minimum thickness for deflection control, solved for the span, with the (0.4 + fy/100,000) non-Grade-60 modifier and the lightweight-concrete factor, by name.
Audience
This tile is built for trades and the adjacent professions in the Carpentry and Construction group. The interactive calculator runs entirely in your browser. No account, no fee, no advertising, no tracking.
Related tools
Posture
Rough Logic answers the math question the working professional asks on the job. The site is a calm, fast, ad-free, account-free, ever-free reference. It does not interpret code. It does not replace the licensed professional. It does not store your inputs. The Authority Having Jurisdiction governs all installations and inspections.