Frequently Asked Questions
Common questions about how these calculators work and how to get a reliable order from them.
Frequently asked questions
Are these calculators free?
Yes. Every calculator is free with no sign-up. The site is supported by advertising.
Do you save the numbers I enter?
No. All calculations run in your browser. Nothing you type is sent to us or stored anywhere. See the privacy policy for details.
How accurate are the results?
The math is exact for the shapes and sizes you enter. Real projects vary: ground is uneven, boards warp and suppliers' bag and pallet sizes differ. That is why each calculator has a waste allowance and lets you change bag, box and pallet sizes.
How much extra should I order?
It depends on the material and the shape of the job. 5% to 10% is typical for simple shapes, and 15% or more for diagonal patterns, curves and complex roofs. Our guide on how much extra to buy lists allowances by project.
Why do my supplier's numbers differ from yours?
Suppliers may use different bag yields, pallet sizes or weights per cubic yard. Enter their figures in the calculator, or ask them which conversion they use.
Can I use these results instead of a contractor's quote?
Use them to plan, budget and check quotes. They do not cover structural design, permits or site conditions. For decks, roofs and anything structural, follow local codes and consult a professional.