The Transformer Calculator helps determine the relationship between the voltages and coil turns in a transformer. It uses the principle V₁/V₂ = N₁/N₂, where V₁ and V₂ are the primary and secondary voltages, and N₁ and N₂ are the number of turns in each coil. By comparing these ratios, the calculator identifies whether the transformer is a step-up (increases voltage) or step-down (decreases voltage) type. This tool is useful for understanding transformer design, efficiency, and voltage conversion in electrical circuits.