Density Symbol (ρ)

Density Symbol uses ρ for mass density. The common definition ρ = m/V states that density is mass divided by volume. A numerical result must include an appropriate unit, such as kg/m³ or g/cm³, and should identify the material and conditions when those details affect the value. Examples on the page include water density, a material table entry, a spatial density field ρ(x, y, z), and the reciprocal relation between density and specific volume. These are physical-quantity examples rather than general Greek-letter examples. They show why the variable needs a definition and unit. The same U+03C1 character is lowercase Greek rho. The Rho Symbol page covers the letter itself, case, and general variable use. This page is restricted to density so that a search for “rho symbol” and a search for “density symbol” do not produce two interchangeable articles. Formatting should keep ρ visually separate from Latin p and should preserve superscripts in units such as m³. A table should not place a bare number under a rho heading unless the unit and material context are visible. Accessible math can read the expression as “density equals mass divided by volume.”. The existing Unicode and NIST measurement sources support the character and quantity-formatting guidance. The page does not expand into unrelated uses of rho unless a separate source and intent are approved. Examples such as Density definition: ρ = m / V, Water density: ρ ≈ 1000 kg/m³, Density field: ρ(x, y, z), Material table: ρ = 7.85 g/cm³, and Specific volume relation: v = 1 / ρ define the operational range of Density Symbol. The Density Symbol use cases are physics equations, engineering reports, measurement tables, and science education, not unrelated image, logo, or broad-symbolism queries. Put a space between the numerical value and SI unit. Keep ρ consistent throughout the equation set. For Density Symbol, Unicode, W3C/WCAG, WHATWG HTML, and NIST provide the evidence base, while density and Greek Small Letter Rho remain accepted lookup labels.