Abstract: A method for radiometric calibration of an infrared detector, the infrared detector measuring a radiance received from a scene under observation, the method comprising: providing calculated calibration coefficients; acquiring a scene count of the radiance detected from the scene; calculating a scene flux from the scene count using the calculated calibration coefficients; determining and applying a gain-offset correction using the calculated calibration coefficients to obtain a uniform scene flux. In one embodiment, the method further includes transforming the uniform scene flux to a radiometric temperature using the calculated calibration coefficients.