Compressed Air Leak Cost Calculator
How much free air a set of leaks lets out at your network pressure, the compressor power it takes and what that costs in electricity per year.
Results
What this tool does
Above roughly 0.9 bar gauge the air leaves a hole at the speed of sound, so the flow grows in step with the absolute pressure and with the square of the diameter: a 2 mm leak loses four times as much as a 1 mm one. The US Department of Energy estimates that leaks often take 20 to 30 % of a compressor's output, and they run every hour the network is pressurised, weekends included if nobody shuts it off. A sharp-edged hole has a discharge coefficient of about 0.61 and a smooth rounded one close to 1; cracked hoses and worn fittings usually sit near the lower end. A modern screw compressor at 7 bar needs around 6 to 7 kW for each cubic metre per minute it delivers, more if it is old or often running part-loaded.
Formula
Q = Cd × A × (p₀ ÷ pₐ) × (2 ÷ 2.4)³ × √(1.4 R T) (choked) · kW = Q × specific power · cost = kW × hours × price
Variables
| Symbol | Meaning | Unit |
|---|---|---|
dh | Diameter of each leak (equivalent hole) | mm |
pg | Network pressure (gauge) | bar |
cd | Discharge coefficient | — |
nl | Number of leaks | — |
hy | Hours a year the network is under pressure | h |
sp | Compressor specific power | kW per m³/min |
ep | Electricity price | per kWh |
CY | What the leaks cost per year | — |
QL | Air lost through the leaks (free air) | L/min |
QM | The same, per hour | m³/h |
CF | The same, in cubic feet per minute | cfm |
PW | Compressor power spent on the leaks | kW |
EY | Electricity wasted per year | kWh |
Worked example
- Diameter of each leak (equivalent hole)1 mm
- Network pressure (gauge)7 bar
- Discharge coefficient0.65
- Number of leaks10
- Hours a year the network is under pressure6000 h
- Compressor specific power6.5 kW per m³/min
- Electricity price0.15 per kWh
- What the leaks cost per year2815
- Air lost through the leaks (free air)481.2 L/min
- The same, per hour28.87 m³/h
- The same, in cubic feet per minute16.99 cfm
- Compressor power spent on the leaks3.13 kW
- Electricity wasted per year18,765 kWh
Limitations
- The result is an estimate based only on the values you type. Real situations often include factors this calculator does not know about.
- The formula assumes ideal conditions: no friction losses, no air resistance and no efficiency losses unless you enter them.
- The tool works with whatever currency you use for the inputs; it does not convert between currencies.