How this calculator works
Convert mass density to molar density, then use the exact Avogadro constant to count atoms. A carrier multiplier estimates free electrons if a simple conduction model assigns a fixed number per atom. Molar mass is entered in g/mol. This chemical counting model is distinct from thermal generation of intrinsic carriers in a semiconductor.
Formula
n = z rho NA / M, where M is in kg/mol and NA = 6.02214076 x 10^23 mol^-1.
Worked example
For rho = 1000 kg/m3 and M = 100 g/mol, one carrier per atom gives n = 6.02214076 x 10^27/m3. Two carriers per atom double it.
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Frequently asked questions
How do I count atoms instead of electrons?
Set carriers per atom to one to obtain the atom count per unit volume.
Is valence always the conduction-electron count?
No. Band structure determines mobile carrier behaviour; a simple valence count may not describe a real material.
Why does molar mass use g/mol?
That is the common chemical convention. The calculation converts it to kg/mol to match mass density in SI.