Interferometric sensors traditionally have been limited by their non-linear input-output characteristics. This paper presents a method for output linearization using four interferometer outputs corresponding to ±sin ct and ±coscp, where 4 is the relative phase of interferometer legs. These outputs are combined in an arctangent algorithm to extract (/). Applications to both Mach-Zehnder and Sagnac interferometers are discussed, with experimental data from a fiber gyro presented. The data taken over a 47r range of 4 demonstrate linearity and stability of the algorithm.