About this calculator
A right-triangle slab is half a rectangle: base × height ÷ 2 gives the area, times thickness gives the volume. Measure the two sides that meet at the square corner, enter the thickness, and you'll get yards, bags, and cost. For any other triangle, measure the longest side as the base and the straight-line distance from it to the opposite point as the height.
How the math works
Triangle area is base × height ÷ 2 — exactly half the rectangle that contains it. Multiplied by thickness (converted to feet) that gives cubic feet, divided by 27 gives cubic yards. An odd four-sided pour can be split into two triangles: run each through the calculator and add the results.
Common questions
How do I measure a triangle pour?
Pick the longest straight edge as the base. The height is NOT the other edge — it's the perpendicular distance from the base to the far point. Lay a string square off the base to measure it honestly.
What about a triangle with no square corner?
Base × height ÷ 2 works for any triangle as long as the height is measured perpendicular to the base. If it's easier, box the triangle into a rectangle mentally — the triangle is always exactly half.
How thick should a triangular pad be?
Same rules as any slab: 4 inches for foot traffic and equipment pads, 5–6 inches if vehicles will cross it. Corners of acute triangles crack first — ask your finisher about rounding the sharp point.