Pharmaceutics
Density Calculator
Calculates the true, bulk or tapped density of a pharmaceutical material from its mass and volume.
True density
Enter a mass and a volume greater than zero to see the density.
Inputs
The weighed mass of the sample.
Volume of the solid itself, e.g. by pycnometry.
Common materials — fills 100 g and the matching volume
Common densities
ρ = m / V
ρ_bulk = (m_total − m_container) / V
ρ_tapped = m / (V_total − V_container)
ρ = density (g/mL), m = mass (g), V = volume (mL). The container terms are optional: use them when the powder was weighed in, or its volume read together with, a container.
For true density the interpretation compares the result with water (1 g/mL): below 1 the material floats, 1–2 g/mL is typical of pharmaceutical powders, and 2 g/mL or more is a high-density material.
Keep learning
References
- Sinko PJ, editor. Martin's Physical Pharmacy and Pharmaceutical Sciences. 8th ed. Philadelphia: Wolters Kluwer; 2023.
- Aulton ME, Taylor KMG, editors. Aulton's Pharmaceutics: The Design and Manufacture of Medicines. 6th ed. Edinburgh: Elsevier; 2022.
Common questions
Bulk volume includes the air between and inside particles, so the same mass is spread over a larger volume. True density counts only the solid, which is why it is always the highest of the three.
Usually by gas (helium) pycnometry, which measures the volume of the solid by gas displacement. Helium penetrates the smallest pores, so the volume excludes voids.
Convert first. The calculator divides the numbers as entered and labels the result g/mL, so mass must be in grams and volume in millilitres.
Use them together to judge powder flow — Carr's index and the Hausner ratio are both calculated from bulk and tapped density. See the Powder Flowability and Compressibility Index calculators.
Prepared by the PharmaWallah student team. Verify results with your textbook or instructor. Report an error · Editorial policy