Disclaimer

Every number on How Many Bags is an estimate for buying material. It is how many bags, cubic yards, tons, boards or fasteners a job is likely to take from the measurements you type in. Read this page before relying on a result for anything beyond a shopping list.

Estimates only

The calculators apply published figures (bag yields, densities, board sizes, common layer depths) to your measurements. They cannot see your site. Soft subgrade, uneven forms, a wet load, a supplier's product that weighs more or less than the published figure, cuts and spills all change what a job takes. Treat every result as a starting point and add the waste allowance the page suggests. Confirm quantities with your supplier before a large order or a delivery you cannot send back. How Many Bags is not responsible for material bought short or in excess, for delivery or restocking charges, or for any loss that follows from relying on a result.

No load, structural or code advice

Nothing on the site says whether a slab, footing, post, wall, deck, driveway or any other structure is strong enough, safe, or compliant with a building code. Thickness, depth, spacing and span figures on the pages are common starting points from the maker, trade or extension documents listed at the end of each page. They are there so you can estimate quantity, not so you can skip the design step. Your local building code, the product maker's instructions and the conditions on your site take precedence over every figure here.

When a permit or an engineer matters

Many jobs these calculators help you shop for need a permit, an inspection or both. Among them are decks above a certain height or attached to a house, footings and foundations, and retaining walls above a certain height. So are driveway aprons that meet a public road and any concrete or asphalt work that changes drainage. A structure that carries people or vehicles, stands more than a step above grade, holds back soil, or sits in frost, expansive clay or fill is an engineering job. Its sizes come from a licensed engineer or from the code tables your building department applies, not from a quantity calculator. Call your building department before you build, and call 811 before you dig so the buried utilities are marked.

Costs

Prices appear as ranges from named documents (government bid tabulations, producer price surveys, published industry reports), with the published figures each range is built from. Otherwise they are figures you type in yourself. They are not quotes. Delivery, minimum-load charges, taxes and regional differences are not in any range unless the page says so.

Sources and corrections

Each calculator and guide lists the documents its figures come from and the date they were read. Documents change. If a figure looks out of date or wrong, write to hello@howmanybags.net with the page and the number. The page is checked against the source and corrected where the report is right. The terms of use and the privacy policy apply alongside this page.