Compressed Air Leak Cost Calculator
Estimate how much air and money compressed-air leaks waste: flow through each hole from pressure and diameter, compressor power, energy and yearly cost — the US DOE orifice method.
How it works
Free-air flow per leak Q = Cd × A × P₀ × √(k ÷ (R·T₀)) × (2 ÷ (k + 1))^((k+1)/(2(k−1))) ÷ ρ_std (choked flow, k = 1.4, P₀ absolute) · power = total flow (m³/min) × specific power (kW per m³/min) · cost = power × hours × price
Air escaping through a hole at normal plant pressures (above about 1 bar gauge) reaches the speed of sound, so the flow depends only on the hole area and the absolute pressure upstream. This is the same choked-orifice relation behind the US Department of Energy leak table (the DOE table lists 6.3 cfm through a 1/16″ hole at 100 psig for a rounded orifice; this calculation gives 6.5 cfm), multiplied by a discharge coefficient for the real shape of the leak. Each unit of air costs compressor electricity — roughly 18 kW for every 100 cfm on a typical rotary screw — and leaks commonly waste 20–30% of a plant’s compressed air.
Worked example
Ten sharp-edged 3 mm leaks on a 7 bar system each lose 6.8 L/s of free air, 67.7 L/s in total (4.06 m³/min). At a typical 6.4 kW per m³/min that wastes 26.0 kW; over 6,000 hours it is 156,071 kWh, which at 0.12 per kWh costs $18,728.57 a year — $1,872.86 per leak.
Sources: US DOE — Compressed Air Tip Sheet #3: Minimize compressed air leaks · Wikipedia — Choked flow
Frequently asked questions
How much does a compressed air leak cost?
A single 3 mm (1/8″) leak at 7 bar (100 psig) loses roughly 7–11 L/s (15–25 cfm), which needs 2.5–4 kW of compressor power — typically 1,500 to 2,500 a year at 0.12 per kWh if the system runs most of the year.
How do I find compressed air leaks?
Listen and use soapy water during quiet hours, or use an ultrasonic leak detector during production. Tag each leak, estimate its size, and fix the largest first; quick-connects, hoses, filters, regulators and drains are the usual culprits.
How can I measure the total leakage of my system?
With no production running, time how long the compressor runs loaded versus unloaded: leakage % = load time ÷ (load + unload time) × 100. Or time the pressure decay of a known receiver volume.
Why does the system pressure matter so much?
Choked flow through a hole is proportional to absolute pressure, so a leak at 8 bar loses about 12% more air than at 7 bar. Lowering the header pressure to what users really need reduces both leakage and compressor power.
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This calculator is for educational purposes. Double-check important results before acting on them.