The efficiency of a generator is calculated using the formula: Efficiency (η) = Output Power / Input Power * 100% Here’s how you can do it: Measure the Output Power: This is typically measured in watts or kilowatts. You can use a power meter to measure the electrical power that the generator is producing. Calculate the Efficiency: Divide the output power by the input power and multiply by 100 to get the efficiency percentage. Please note that this calculation assumes that the generator is operating at its rated load. Generators often operate less efficiently at lower loads. Also, keep in mind that some energy is always lost as waste heat, so no generator will be 100% efficient.