Triangle Concrete Calculator

Why This One Is Different

That leftover triangular patch between two driveways, or the wedge you're cutting off a patio corner, still needs a real yardage number before you call in a concrete order. A triangular slab is mathematically half of the rectangular prism you'd get by mirroring it, which is why this calculator reuses the wedge-ramp formula behind the scenes (volume equals length times width times thickness, divided by two). The field usually labeled "height" on a ramp becomes your slab's uniform thickness here, since a flat triangular slab doesn't taper the way a ramp does: only the footprint is triangular, not the depth. A 10×8 ft right-triangle slab at 4 inches works out to about 13.3 cubic feet, or roughly 0.5 cubic yards, before the ordering allowance.

Where the Numbers Come From

• Your triangular slab's volume comes from the same half-prism shortcut every time: for a right-triangle footprint with legs L and W poured at uniform thickness T, volume = ½ × L × W × T, algebraically identical to the wedge-ramp formula with T substituted for rise. Source: worked example, closed-form geometry
• A 10×8 ft right-triangle slab at a 4-inch uniform thickness works out to 13.3 cubic feet (½ × 10 × 8 × 0.333), or about 0.49 cubic yards, before any ordering allowance. Source: worked example, closed-form geometry
• NRMCA guidance is to order 4-10% more than plan-derived volume for any formed pour, applying to triangular footprints the same as rectangular ones. Source: NRMCA, CIP 8: Discrepancies in Yield (2021 reprint)