Conduit fill is the percentage of the area inside the conduit taken up by the cable(s). Consult applicable codes, industry standards, and manufacturers' data for further information on fill. Dimensions and percent area of conduit and tubing are typically provided in tables.

Dimensions for various types of conduits can be found e.g. in Chapter 9 of the 2005 National Electrical Code.

Symbol
$CF_{\mathrm{p}}$
Unit
%
Formulae
$\frac{D_{\mathrm{e}}^{2} N_{\mathrm{c}}}{100 Dd_{i}^{2}}$
Related
$D_{\mathrm{e}}$
$N_{\mathrm{c}}$