A standard candle is an object with a known luminosity, or, equivalently, a known absolute magnitude. To obtain the distance to the object one still has to use:

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The distance modulus equation is used to calculate the distance to an object based on its known absolute magnitude and apparent magnitude. The inverse-square law is used to determine the brightness of an object at a certain distance from an observer, but it does not provide the distance itself. Kepler's third law relates the orbital period and distance of a planet to its parent star, but it is not applicable to standard candles. The Hubble law is used to determine the expansion rate of the universe and the distance to galaxies, but it requires the observation of redshifts and is not specific to standard candles.

A Standard Candle Is an Object with a Known Luminosity