Abstract When 26.8Ah (1Faraday) of electrcity pass through an electrochemical cell, 1g equivalent of mass is formed or dissolved at the electrodes through the electrochemical reaction. The electrochemical equivalent weights of the active materials in a lead–acid cell per Ah are 3.866g Pb Ah−1 (for the Pb/PbSO4 electrode) and 4.463g PbO2 Ah−1 (for the PbO2/PbSO4 electrode). The total weight of the positive or negative active material in a cell is equal to the sum of the weights of the energetic (Ge ) and skeleton (Gs ) structures. There are three parameters used for calculating the actual amount of active materials needed for producing a cell of a given capacity: active mass utilization coefficient (η); active mass weight coefficient per Ah (β); specific capacity of positive active mass (PAM) or negative active mass (NAM) per kg active mass (σ). The working concentration region of H2SO4 in the cell is between 1.5 and 5.0M (i.e., from 1.10 to 1.25 relative density). It can generate 72Ah of electricity. Examples for the following calculations are presented in the chapter: 1. active materials in a 50Ah SLI cell at 50% utilization of PAM and 45% NAM utilization; 2. paste composition; 3. amounts of H2O and H2SO4 in a lead–acid cell; 4. active materials for various types of lead–acid batteries; 5. volumes of H2O and H2SO4 solution needed for paste preparation; 6. quantity of electricity needed for formation of the cured plates; 7. potentials of Hg/HgSO4 and Ag/Ag2SO4 reference electrodes (used for measuring cell electrode potentials) at different H2SO4 concentrations and temperatures.