How do you calculate the cost of a compressed air leak?

Take the leak's flow from the US DOE table for its approximate hole size and the system pressure, multiply by the compressor's kW per 100 cfm divided by 100 to get kW, then by the hours a year the system is under pressure and the price per kWh. A 1/16 inch sharp-edged leak at 100 psig: 6.5 × 0.61 = 3.97 cfm; 3.97 × 18 ÷ 100 = 0.71 kW; 0.71 × 6,000 h × $0.10 = $428 a year.

How much air do leaks waste in a typical plant?

The US Department of Energy's tip sheet on leaks says they often waste as much as 20 to 30% of a compressor's output. Its sourcebook adds that a plant that has not been well maintained will likely leak about 20% of its production capacity, and that a leak program can bring that under 5 to 10%. Measure your own with a load/unload or pressure decay test rather than assume.

What kW per 100 cfm should I use?

The figure from your compressor's data sheet at your pressure. DOE's worked example uses about 18 kW per 100 cfm, and the DOE sourcebook gives full-load ranges at 100 psig from 15 to 16 for double-acting reciprocating machines to 22 to 24 for single-acting air-cooled ones, with lubricant-injected screws at 16 to 19 (single-stage). In metric, divide kW per 100 cfm by 2.83 to get kW per m³/min.

Why multiply by 0.61 for a sharp-edged hole?

The DOE table gives the flow through an ideal orifice. Its footnote says to multiply by 0.97 for a well-rounded hole and 0.61 for a sharp-edged one, because less air gets through a sharp edge. DOE's own worked example uses 0.61, and so does this calculator by default, so the estimate is not inflated. Choose the table values as printed only if you have reason to.

Will fixing the leaks cut the electricity bill by this much?

Only if the compressors then use less power. The sourcebook says the compressor controls must be re-evaluated after leaks are repaired to realise the savings, and the 2004 tip sheet says compressor run time has to fall to match the lower demand. A compressor that keeps running unloaded, or a second machine that stays on, keeps some of the cost. The calculator uses full-load specific power, so treat its figure as the most a fix can save.

How do I measure total leakage?

With production off. For a start/stop or load/unload compressor, time several load and unload cycles: leakage % = 100 × on-load time ÷ (on-load + off-load time). For other controls, pump the system to working pressure, then time the fall to about half: cfm = volume in cubic feet × (P1 − P2) ÷ (minutes × 14.7) × 1.25. Both come from the DOE sourcebook. Equipment with its air valve shut is not counted.

Does lowering the pressure reduce leaks?

Yes. Flow through a leak rises with supply pressure, so a lower, stable header pressure leaks less, as the DOE sourcebook notes. The table shows it: a 1/16 inch leak passes 7.9 cfm at 125 psig and 6.5 cfm at 100 psig. Lower the pressure only as far as the end users still work.

Can I use bar and litres per second?

Yes. Switch the units to bar, L/s and m³ and every typed value is converted. The DOE table is in psig and cfm, so the calculator converts: 1 bar = 14.50 psi, 1 cfm = 0.472 L/s. The table covers 70 to 125 psig, which is 4.8 to 8.6 bar gauge.

Should we tag leaks or fix them on the spot?

The DOE sourcebook describes both: seek and repair, where the leak is fixed when found, and a leak tag program, where a two-part tag stays on the leak and the other half goes to maintenance. It says the best is often a mix, and that every leak should still be logged, with tags no substitute for a master list. The tag log above is that list.

Free tool

Compressed air leak cost calculator

A compressed air leak costs the electricity the compressor burns to make the air that escapes. Enter each tagged leak's approximate hole size, or a detector's flow reading, and the system pressure to get the air lost, the kW wasted and the cost a year from the US Department of Energy's leak table, with the leaks ranked so the biggest gets fixed first.

Leak flow, cfmequalsDOE table value (hole size, pressure) × C

kWequalscfm × specific power (kW per 100 cfm) divided by 100

Cost a yearequalskW × hours under pressure × price per kWh

Leakage, % of capacityequals100 × on-load time divided by on-load time + off-load time

C is 0.61 for a sharp-edged hole and 0.97 for a well-rounded one (the table footnote). Table and cost formula: US DOE Compressed Air Tip Sheet #3, Minimize Compressed Air Leaks (2000). The load/unload test, run with production off, and the pressure decay test are in Fact Sheet 3 of the DOE sourcebook, Improving Compressed Air System Performance (3rd ed., 2016).

Units

Pressure at the leaks

Gauge pressure. The DOE table covers 70 to 125 psig.

Leak shape

The DOE footnote's factor for the hole. DOE's own example uses sharp-edged.

Compressor specific power

From the compressor's data sheet. DOE's example uses 18.

Hours a year under pressure

Leaks blow whenever the system is pressurised, production or not.

Electricity price

Currency

Compressor capacity (optional)

To show the leaks as a share of it.

Leak tag log

One row per tagged leak. Pick the nearest hole size, or choose Flow reading and enter what the ultrasonic detector or a flow meter says.

Tag
Size
Where
1.6 mm hole: 3.97 cfm, $428 a year
Fixed (T-01)
Tag, leak 2
Size, leak 2
Where, leak 2
0.8 mm hole: 0.98 cfm, $105 a year
Fixed (T-02)
Tag, leak 3
Size, leak 3
Where, leak 3
3.2 mm hole: 15.86 cfm, $1,713 a year
Fixed (T-03)
Tag, leak 4
Size, leak 4
Where, leak 4
1.6 mm hole: 3.97 cfm, $428 a year
Fixed (T-04)
Tag, leak 5
Size, leak 5
Where, leak 5
0.8 mm hole: 0.98 cfm, $105 a year
Fixed (T-05)
Tag, leak 6
Size, leak 6
Where, leak 6
0.8 mm hole: 0.98 cfm, $105 a year
Fixed (T-06)
Tag, leak 7
Size, leak 7
Where, leak 7
0.4 mm hole: 0.25 cfm, $27.01 a year
Fixed (T-07)
Tag, leak 8
Size, leak 8
Where, leak 8
Flow reading, leak 8
Fixed (T-08)

Whole-system test with production off (optional)

Average on-load time

Average off-load time

Pre-filled with the worked example (illustrative). Hole sizes are estimates of the equivalent orifice, so treat the costs as estimates too.

Leaks found cost a year

$3,345

8 leaks: 30.97 cfm, 5.57 kW, 33,446 kWh a year.

Still open

$3,239

7 open, 29.99 cfm

Fixed so far

$105

1 fixed, a year saved if the compressor runs less

Air lost

30.97 cfm

14.6 L/s

Share of capacity

12.4%

DOE: under 5 to 10% when well maintained

Fix the biggest first: share of the cost

1. T-03$1,713 · 51.2%

2. T-08$432 · 12.9%

3. T-01$428 · 12.8%

4. T-04$428 · 12.8%

5. T-02$105 · 3.2%

Whole-system test, production off

46.88 cfm · 18.8% of capacity

About $5,063 a year. The tagged leaks account for 66% of it; the rest is still to find.

Over 10 percent: the DOE sourcebook says a well-maintained system should be under 5 to 10 percent.

Repair list, biggest first

The tag log sorted by cost a year. Copy it into a spreadsheet or your maintenance system.

Tagged leaks ranked by cost a year
#	Tag and place	Size	cfm	kW	A year	Status
1	T-03 · Receiver drain stuck open	1/8 in	15.86	2.85	$1,713	Open
2	T-08 · Valve manifold, detector reading	Reading	4	0.72	$432	Open
3	T-01 · Quick coupler, press 3 drop	1/16 in	3.97	0.71	$428	Open
4	T-04 · Split hose, blow-off station	1/16 in	3.97	0.71	$428	Open
5	T-02 · Filter bowl seal, cell 4	1/32 in	0.98	0.18	$105	Open
6	T-05 · Cylinder rod seal, fixture 2	1/32 in	0.98	0.18	$105	Open
7	T-06 · Threaded union, main header	1/32 in	0.98	0.18	$105	Fixed
8	T-07 · Push-in fitting, case packer	1/64 in	0.25	0.05	$27.01	Open

Flow = table value at 100 psig × 0.61. kW = cfm × 18 ÷ 100. Cost = kW × 6,000 h × 0.10 USD per kWh, so each cfm costs $108 a year.

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Before you enter numbers

Getting numbers you can trust

Find and size the leaks. DOE calls an ultrasonic detector the best way to find leaks: it picks up the high-frequency hiss and is loudest at the leak. Soapy water on a brush also works but is slow. A hand-held detector gives an indication of size, so pick the nearest table hole size, or enter the detector's flow reading if it gives one. Never feel for a leak with your hand.

Use the pressure at the leaks. That is the header or drop pressure, not the compressor discharge setting if there is a drop in between. The DOE table runs from 70 to 125 psig; between its rows the calculator draws a straight line, which is how the table itself behaves.

Take specific power from the compressor data sheet. It is the compressor input power per 100 cfm it delivers. The table further down gives the sourcebook's typical ranges if you have nothing better; change the value to see how much it matters.

Count every pressurised hour. Leaks blow on breaks, weekends and idle shifts if the compressors stay on. Use the hours the system is under pressure, up to 8,760 a year, and your average price per kWh from the electricity bill.

Check the total with a test. A walk never finds every leak. The whole-system test, with production off, shows how much leakage there is in total, so you know how much is still to find.

Worked example

Illustrative numbers, not a benchmark

A Saturday leak walk with an ultrasonic detector on a 100 psig system: eight leaks tagged. The plant uses 18 kW per 100 cfm, keeps the system pressurised 6,000 hours a year and pays $0.10 per kWh. The compressor delivers 250 cfm. Holes are taken as sharp-edged.

1Flow per leak from the DOE table at 100 psig, × 0.61: 1/16 inch: 6.5 × 0.61 = 3.97 cfm (two leaks). 1/32 inch: 1.6 × 0.61 = 0.98 cfm (three). 1/8 inch: 26 × 0.61 = 15.86 cfm (one, a receiver drain stuck open). 1/64 inch: 0.41 × 0.61 = 0.25 cfm (one). One valve manifold read 4.0 cfm on the detector.
2Total: 2 × 3.965 + 3 × 0.976 + 15.86 + 0.25 + 4.0 = 30.97 cfm, or 14.6 L/s.
3Power: 30.97 × 18 ÷ 100 = 5.57 kW. Energy: 5.57 × 6,000 h = 33,446 kWh a year. Cost: × $0.10 = $3,345 a year, which is $108 for every cfm.
4Ranked: the stuck drain alone is 15.86 cfm and $1,713 a year, 51.2% of the total. One repair halves the bill. The threaded union on the main header was fixed during the walk ($105); seven leaks worth $3,239 stay open.
5Test with production off: the compressor loads for 1.5 minutes and unloads for 6.5. Leakage = 100 × 1.5 ÷ 8 = 18.75% of 250 cfm = 46.9 cfm, about $5,063 a year. The eight tags account for 66% of it, so a third is still to find, well above the 5 to 10% the DOE sourcebook expects of a well-maintained system.

8 leaks: 30.97 cfm, 5.57 kW and $3,345 a year, half of it one drain. Total leakage 18.75% of capacity, $5,063 a year. The calculator above is filled in with this walk. The numbers are illustrative.

The DOE leak table

Leakage in cfm of free air through an approximately equivalent round hole, as printed in the 2000 tip sheet (used there with permission from the Compressed Air Challenge). Multiply by 0.61 for sharp-edged holes or 0.97 for well-rounded ones.

Leakage rate in cfm by supply pressure and hole diameter, US DOE Compressed Air Tip Sheet 3
Pressure	1/64 in0.4 mm	1/32 in0.8 mm	1/16 in1.6 mm	1/8 in3.2 mm	1/4 in6.4 mm	3/8 in9.5 mm
70 psig4.8 bar	0.3	1.2	4.8	19.2	76.7	173
80 psig5.5 bar	0.33	1.3	5.4	21.4	85.7	193
90 psig6.2 bar	0.37	1.5	5.9	23.8	94.8	213
100 psig6.9 bar	0.41	1.6	6.5	26.0	104	234
125 psig8.6 bar	0.49	2.0	7.9	31.6	126	284

The sourcebook's own leak figure uses the same 6.5, 26 and 104 cfm at 100 psi. The tip sheet's 2004 revision prints every value already multiplied by 0.97 (6.31 instead of 6.5) while keeping the footnote, which is why some calculators give about 3% less. Its worked example also keeps the 2000 total of $57,069, although its own lines add to $55,378. Checked October 9, 2026.

Typical specific power at 100 psig

Typical full-load specific power by compressor type, DOE sourcebook Fact Sheet 7
Compressor type	kW per 100 cfm
Lubricant-injected rotary screw, single-stage	16 to 19
Lubricant-injected rotary screw, two-stage	15 to 17
Lubricant-free rotary screw	17 to 22
Centrifugal	16 to 20
Double-acting, water-cooled reciprocating	15 to 16
Single-acting, air-cooled reciprocating	22 to 24

Full load, from estimated brake horsepower with a 92% efficient motor: DOE sourcebook, Fact Sheet 7. The sourcebook adds that most compressors use more energy per cfm at part load. Your data sheet beats any typical value.

Running a leak program that lasts

How big the prize is. DOE's tip sheet says leaks often waste as much as 20 to 30% of a compressor's output, and suggests 5 to 10% of total system flow as a reasonable target. The sourcebook puts a plant that has not been well maintained at about 20%.

Where to look. The tip sheet lists couplings, hoses, tubes, fittings, pipe joints, quick disconnects, filter-regulator-lubricator units, condensate traps, valves, flanges, packings, thread sealants and point-of-use devices. The sourcebook adds that most leakage is at the point of use, and that equipment no longer used should be valved off.

The steps. Following the sourcebook's Fact Sheet 3: measure a baseline, test the total leak load, put a cost on it, find and tag the leaks, log each one (place, type, size, cost), fix the biggest first, adjust the compressor controls, record the repairs and look for repeat offenders to fix at the root, compare against the baseline and publish the result, then start again, because new leaks keep appearing.

Why the biggest first. In DOE's own example, 10 leaks of 1/4 inch out of 160 were almost 70% of the savings ($39,967 of $57,069 a year at $0.05 per kWh). In the example above, one stuck drain is half.

Hang the free air and water leaks poster by the compressor room, and plan the leak routine as part of an environment and energy 90-day plan.

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How LeanSuite helps

LeanSuite does not measure air flow. Its environment tags let anyone flag an air or water issue on the spot with a photo, route it to an owner and close it with an audit trail, so each leak on this list has someone fixing it.

See Environment Tags

FAQ

Compressed air leak cost calculator: common questions

Only if the compressors then use less power. The sourcebook says the compressor controls must be re-evaluated after leaks are repaired to realise the savings, and the 2004 tip sheet says compressor run time has to fall to match the lower demand. A compressor that keeps running unloaded, or a second machine that stays on, keeps some of the cost. The calculator uses full-load specific power, so treat its figure as the most a fix can save.
With production off. For a start/stop or load/unload compressor, time several load and unload cycles: leakage % = 100 × on-load time ÷ (on-load + off-load time). For other controls, pump the system to working pressure, then time the fall to about half: cfm = volume in cubic feet × (P1 − P2) ÷ (minutes × 14.7) × 1.25. Both come from the DOE sourcebook. Equipment with its air valve shut is not counted.

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