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Where our figures come from

Every number on this site is your own measurement run through our arithmetic, a figure a maker or supplier publishes for its own product, or a figure from an extension service, a government agency, a standards body or a trade association. This page lists every publisher we take figures from. A maker’s specification or manual does not change once the product exists, so it carries its link and nothing else. Laws and regulations can change, so each of those shows the date we last read it.

Your measurements and our arithmetic

The calculators start from the dimensions you enter. Unit conversions use the definitions in NIST Handbook 44: 12 inches to a foot, 3 feet to a yard, exactly 0.3048 meters to a foot and 2,000 pounds to a US ton. The formulas behind each result are set out on the calculation methods page.

Extension services, government agencies and standards

University extension services, government agencies, standards bodies and the Square Foot Gardening Foundation for its own soil recipe. Depths, widths, safety limits and unit definitions come from these.

Raised bed makers

Each bed’s sizes, heights, materials and stated soil capacity come from its maker’s own product page, specification sheet or assembly guide.

Watering kit makers

Parts lists, tubing lengths, pressure figures and stated bed coverage come from each kit maker’s product page and installation manual.

Materials, suppliers and trade associations

Example weights per cubic yard, bag yields, pallet sizes, minimum loads and allowances come from the supplier or maker named beside them, and apply to its products. Lumber sizes and fastener guidance come from the wood trade associations.

How we keep these current

When a maker changes a figure, we update it here and on the page that uses it.

What we owe these publishers

NIST Handbook 44 is a US government publication, free to reuse. Extension and agency pages are cited by name and link. Product photographs are shown from Amazon under the Amazon Associates program and belong to their owners; they are not stored on this site.