This article deals with a noise analysis of inertial sensors, especially with accelerometers. Accelerometers and gyroscopes are inertial sensors which are parts of inertial measurement units IMUs. An inertial navigation uses outputs from three accelerometers and from three gyroscopes to positions, orientations computations. For better accuracy of navigation and guidance systems is necessary to evaluate deterministic and stochastic inertial sensors errors. Main aim of this article is to introduce new algorithm for Allan variance computation. Part of this article deals with the new practical experience with using of the Allan variance for noises and noise coefficients determination.