Calculation Disclaimer

BuildLumi calculators give planning estimates of material quantities. Read this page before you order materials or start work.

Planning estimates only

Results depend on the numbers you enter and on assumptions such as waste, compaction, density and bag size. Real jobs differ: forms bow, subgrades are uneven, material settles, and cuts and breakage vary with the installer. Treat each result as a starting point and add the allowance that fits your job.

Not engineering, structural or code advice

The calculators estimate quantities. They do not determine slab thickness, footing size, reinforcement, post depth, beam, joist or rafter size and span, deck ledger attachment, railing loads, roof structure, fire ratings or any other requirement of a building code. Those depend on your soil, climate, loads and local rules.

• Check with your local building department about permits, setbacks, height limits and inspections.
• Hire a licensed engineer or contractor for structural work.
• Call 811 before you dig.

Products vary

Bag yields, coverage per bundle or gallon, and material weights differ by brand, product and moisture. Use the figure printed on your product label or in the manufacturer’s data sheet, and ask your supplier when a number matters. Where a calculator offers a default, you can replace it. Product names on this site identify the documents we used and do not imply any affiliation or endorsement.

Ordering too much or too little

BuildLumi is not responsible for materials you order in excess or fall short of, for delivery or short-load charges, or for the cost of rework or delay. Check your supplier’s minimums, units and return policy before you order.

Safety

Construction involves risk. Wear suitable protection, follow manufacturer instructions, and respect fall, dust and chemical hazards. Wet concrete can burn skin, roofing work carries fall risk, and sanding drywall produces dust you should not breathe.

More information

How the numbers are chosen is explained on the methodology page. Use of the site is also covered by the terms of use. To report a problem, write to [email protected].