dryweight

Dry weight is the mass of a substance after its moisture content has been removed. It represents the intrinsic, water-free mass and is used to compare material on a consistent basis. The term is often contrasted with wet weight or as‑is mass, which includes all water present at the time of weighing. Dry weight is a common metric in botany, agriculture, pharmacology, and food science because moisture can vary widely between samples.

In laboratory practice, dry weight is typically determined by drying a sample in an oven at a specified temperature (often around 100–105°C) until a constant weight is reached. This procedure, part of the loss-on-drying method, removes water and yields the dry mass. Alternative approaches include freeze-drying or the use of moisture analyzers. The moisture content can then be calculated as the difference between the initial wet weight and the final dry weight.

Applications of dry weight span several fields. In plant biology and agronomy, dry weight provides a stable basis for reporting tissue biomass, seed mass, or crop yields. In ecology, it enables comparisons of organismal biomass without moisture variation. In pharmacology and herbal products, dosages are sometimes expressed on a dry-weight basis to reflect the actual active matter independent of water content.

Notes and caveats are important. Different materials require different drying conditions, and excessive heat can degrade or alter components, affecting the measured dry weight. A true dry weight is achieved when successive weighings show no significant change, defining a constant weight.