This part of ISO16063 specifies the instrumentation and procedure to be used for the accurate calibration of seismometer sensitivity using local gravitational acceleration (local Earth’s gravitation; local value for the acceleration due to the Earth’s gravity) as a reference value. It is intended generally to be applied to a servo-type accelerometer with/without a velocity output, which usually has a mass position output in the category of a wide-band seismometer with a bandwidth from 0,003Hz to 100Hz. The method specified enables the user to obtain static sensitivity for the seismometers up to 10−5m/s2 (which corresponds to 1mGal and approximately 1ppm of the gravitational acceleration). The combined and expanded (k=2) uncertainty of applied acceleration achieved by this method is 10−6m/s2 (0,1mGal). When the absolute gravimeter described in this part of ISO16063 is used, the uncertainty of applied acceleration can be suppressed to 5×10−8m/s2 (5μGal). The relative expanded uncertainty of calibration, excluding the uncertainty due to the device under test (DUT), is 0,5%. The intended end-usage of the seismometer to be applied is as follows: measurement and observation for the earth science including geophysics usage; measurement and observation for disaster prevention, such as detecting the precursor of a land slide; diagnosis for the soundness of a building structure and foundation soil in civil engineering; observation for nuclear-test detection.