Deflection Limit Calculator
Check deflection limits for beams and slabs per ACI 318 serviceability requirements.
Member Parameters
ft
in
Deflection Check
OK
0.5" vs 0.500" allowable (L/480)
Allowable Deflection
0.500"
Actual L/Ratio
L/480
Utilization
100.0%
Margin
0.0%
Deflection Limits (ACI 318):
Span Length20 ft (240")
Limit RatioL/480
Min Depth (no calc)15.0" (L/16)
Limit DescriptionFloor supporting partitions (L/480)
ACI 318 Reference
Deflection limits per ACI 318-19 Table 24.2.2. Minimum thickness per Table 9.3.1.1 to avoid deflection calculations. Long-term deflection multiplier = 2.0 for 5+ years.
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Editorial Note
MyCalcBuddy Editorial Team
This page is maintained as an educational calculator reference.
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Formula Source: Standard Mathematical References
by Various
🔄Last reviewed: May 2026
✓Formula checks are based on standard references and internal QA review.