Grade Beam Calculator — ft, yd³, rebar
How to use this calculator
Enter the number of grade beams, length, width, and depth. A grade beam is a reinforced concrete beam at or near ground level that spans between piers, piles, or footings. Adjust waste allowance and get instant volume, weight, and bag count results.
Cost — pick ready-mix per yd³, 80-lb bags, or 60-lb bags.
Reinforcement — longitudinal bars (top + bottom) plus stirrups spaced per ACI 318-19. Lap splices at 40db, 1.5″ clear cover.
Labor — rate per linear foot, per yd³, or flat price.
Saved Calculations
| Time | Beams | Size | Vol yd³ | Concrete $ | Rebar lf | Rebar $ | Labor | Total |
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How to Calculate Concrete for Grade Beams
A grade beam is a reinforced concrete beam at ground level that connects piers, piles, or column footings. This calculator estimates concrete volume in cubic yards, number of pre-mixed bags (60 lb and 80 lb), total weight, reinforcement (longitudinal bars and stirrups), and cost. Enter beam width (typically 12–24″), depth (typically 24–36″), and span length in feet and inches with ⅛″ precision.
Reinforcement per ACI 318-19
Grade beams require top and bottom longitudinal bars (typically #4 to #6) plus closed stirrups (#3 or #4) spaced at d/2 maximum (ACI 318 §9.7.6.2.2). The calculator accounts for lap splices at 40 bar diameters, 1.5″ clear cover, and cutting waste. Standard bar length is 20 ft.
Formulas
Volume per beam = Width × Depth × Length. Total volume = Volume per beam × Number of beams × (1 + Waste%). Stirrup perimeter = 2 × (Width − 2 × cover) + 2 × (Depth − 2 × cover). Stirrup count = Length / Spacing + 1.
FAQ
What size grade beam do I need? For residential construction, 12″×24″ is common for light loads. For larger spans or heavier loads, use 18″×30″ or 24″×36″. Always consult a structural engineer for specific requirements.
