About BuildRule

BuildRule publishes construction material calculators that are free, fast and require no sign-up. Every calculator shows the formula it uses, so you can verify the result instead of taking it on trust.

Where the figures come from

Bag yields follow manufacturers' published figures: 0.60 cubic feet for an 80 lb bag of concrete, 0.45 for 60 lb and 0.30 for 40 lb. Volumes convert at 27 cubic feet to the cubic yard. Brick and block coverage uses nominal dimensions including a standard 3/8 inch mortar joint. Roof area uses the pitch multiplier √(1 + (rise÷12)²).

Accuracy

These are planning estimates. Site conditions, sub-grade variation and local building code all affect what you actually need. Always confirm quantities with your supplier and check requirements against local code before ordering.