Method: Compressor specific power is calculated as: Specific Power = Electrical Input Power ÷ Delivered Airflow when airflow is expressed in m³/min. Specific energy per 1,000 m³ of compressed air is: Specific Energy = Specific Power × (1,000 ÷ 60) This follows because a compressor delivering 1 m³/min requires 1,000 minutes to produce 1,000 m³, equivalent to 16.667 hours. Annual electricity use, when operating hours are entered, is: Energy = Input Power × Operating Hours Annual electricity cost is: Cost = Annual Energy × Electricity Tariff Discharge pressure is included because specific-power values should only be compared at similar pressure and airflow reference conditions. This calculator does not attempt to derive isothermal or adiabatic compressor efficiency from discharge pressure alone. A true thermodynamic efficiency calculation requires inlet conditions, pressure ratio, air temperature, compression stages and additional compressor data. For performance benchmarking, use measured input power and standardized or corrected delivered-airflow data whenever possible.