# Are Heaviside-Lorentz unit and Gaussian unit natural units?

I am studying electromagnetism and have encountered the Heaviside-Lorentz unit and Gaussian unit. In these unit systems, the constant $c$ keeps occurring. For example, the Maxwell equations are of this form. So, I think in these unit systems, $c$ is some nontrivial constant other than $1$. However upon reading the Wikipedia about natural units, it states that the Heaviside-Lorentz unit and the Gaussian unit are natural units and $c=1$. So I am confused. Why does $c$ keep occuring in the two units if $c$ is jus equal to $1$? Could anyone please explain?

• Oh that's poorly written. They become natural if you take $c=1$. – secavara Feb 16 '18 at 15:48
• So, that means I can take $c$ not to be $1$? So, in the above Maxwell equations, $c$ is not $1$ and therefore not omitted? – Keith Feb 16 '18 at 16:05
• Yes, unless you are specified to work in natural units, you are expected to keep the $c$'s in these electromagnetic unit systems. For a complete description of unit systems you can check the appendix in Jackson's book, Classical Electrodynamics, 3ed. – secavara Feb 16 '18 at 16:09