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Thrust Block Calculator
Block Type iBearing block: horizontal bends, tees & dead ends, and concave-up (∪) vertical bends — thrust resisted by the block bearing against undisturbed soil.

Gravity block: concave-down (∩) vertical bends where thrust pushes up out of excavated ground — resisted by the block's weight (plus tie rods around the fitting).
Pipe & Pressure
Soil & Block
Design Assumptions
References & Details

Reference. NFPA 24, Private Fire Service Mains, 2025 Edition — A.10.6.1, Eq. [A.10.6.1a] & [A.10.6.1b], Table A.10.6.1(a) (thrust), Table A.10.6.1(c) (soil bearing), Figure A.10.6.1(b).

Thrust Force (T)
– lbf
Required Bearing Area (Ab)
– ft²
Calculated Block Width (b)
– ft
Bearing Block Calculations
Block Type iBearing block: horizontal bends, tees & dead ends, and concave-up (∪) vertical bends — thrust resisted by the block bearing against undisturbed soil.

Gravity block: concave-down (∩) vertical bends where thrust pushes up out of excavated ground — resisted by the block's weight (plus tie rods around the fitting).
Pipe & Pressure
Block Material
Horizontal Component (Bearing)
References & Details

Reference. NFPA 24, 2025 Edition — A.10.6.1(5), Eq. [A.10.6.1d] (block volume) & [A.10.6.1e] (horizontal component), Figure A.10.6.1(c).

Required Block Volume (Vg)
– ft³
Required Weight (W)
– lbf
Min. Horizontal Bearing Area (Ab)
– ft²
Gravity Block Calculations
×Enlarged diagram
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