Choose a density with a usable basis

Start with the decision the estimate supports

Comparing wood species for a project and documenting the weight of a finished lumber order have different evidence needs. For an early scenario, a clearly labeled assumed density can show which inputs dominate the result. For an actual shipment, ask the supplier for product-specific information or an appropriate weighing. Do not let the precision of the calculator imply that the source material was measured.

Write down the product description first: species identification if known, solid or engineered construction, treatment, profile and condition. A familiar trade name may cover material from more than one botanical species. An average entry in a general reference should not be relabeled as the weight of a particular board pack.

Read the units and condition together

Density relates mass to volume. If the weight and volume refer to different moisture conditions, the resulting figure may answer a different question from the one on your worksheet. The USDA handbook explains the relationship between wood moisture and physical properties. Use that context to ask for the density basis, not to invent a correction factor.

Store the document title, date, units and relevant condition beside the input. A screenshot without the table heading may omit the very information needed to interpret its figures. If only specific gravity is available, use the separate guide before treating it as a density.

Worked scenario: two plausible inputs

Illustrative example: the same 5-cubic-foot quantity at assumed densities of 40 and 50 lb/ft³ produces 200 and 250 lb. The arithmetic is valid in both cases. Choosing the input remains the unresolved decision. These are hypothetical values, not species ratings.

Send the supplier both the quantity basis and the question you need answered: which documented figure applies to the proposed material in its shipping condition? Preserve the original assumption in the record if it is replaced. That history makes a revised estimate understandable without presenting the first figure as a mistake in multiplication.

Evidence & scope