This paper discuss a set of tools for metrological evaluation of optical fiber grating sensors, including uncertainty analysis of the measurements. Background and definitions about basic specifications of the optical fiber grating sensors, such as response curve, calibration curve, sensitivity, resolution, repeatability, reproducibility and conformity are presented. Besides, the paper proposes the procedures to identify, quantify, and express uncertainties in optical fiber grating sensor measurements based on the International Standard Organization's Guide to the Expression of Uncertainty in Measurement. In order to illustrate the application of the approach, two fiber grating measuring systems were evaluated under the light of the methodology. The proposed route is a pragmatic step towards the standardization of optical fiber sensors.