Density

What It Measures

Density describes how much charcoal mass fits in a given volume. Bulk density is the mass of a loosely filled or mechanically settled volume of material, usually expressed in kg/m³. Particle (apparent) density is the mass of an individual piece divided by its envelope volume — the two are different and are not interchangeable.

For a compressed cube or briquette product, bulk density is the commercially relevant figure because it determines how many tonnes fit a container.

Why It Matters

Bulk density decides container loading: a denser product packs more tonnes into a 20′ or 40′ container, lowering freight per tonne. Two products with the same per-kg price can differ substantially in landed cost if their bulk densities differ.

Density also interacts with burn behaviour — denser pieces tend to burn longer — but that relationship is indirect and must not be inferred from a single density figure.

Typical Measurement Method

Bulk density is measured by filling a container of known volume with the material under defined conditions (loose-fill, tapped, or mechanically settled) and weighing it. Public references include ISO 17828 for solid biofuels, which specifies the fill procedure and the reporting basis.

Particle or apparent density is measured differently — for example by weighing a piece and dividing by its measured envelope volume, or by displacement methods. Because the two describe different things, the method must always be stated.

Buyer Relevance

Buyers compare bulk density to estimate container utilisation and freight per tonne. Ask for the fill method and whether the figure is loose or settled, because both change the number.

Because density is also affected by moisture and size distribution, a density figure should be read together with moisture and size grading rather than as a stand-alone value.

Limitations

Density is not a fixed property: it varies with size distribution, moisture, and how the material is filled or settled, so a value is only meaningful with its method and conditions stated.

Bulk density says nothing directly about energy content — two materials of equal bulk density can have different fixed carbon and calorific value. This page describes methodology only and publishes no density figures.

Data Source

Public standard methodology (general); not supplier-specific test data.

Last updated: 2026-10-07

Public methods commonly referenced

• ISO 17828 — Solid biofuels: determination of bulk density
• Container-fill method (mass of a known volume), widely used in trade
• Particle / apparent density methods (different product family from bulk density)

Standard references are given as general, publicly documented method families. Applicability, current edition and reporting basis must be confirmed with the testing laboratory for any specific report.