Air Hose Pressure Drop Calculator
Pick the right hose size. Enter flow, length and pressure to see the loss for every size.
How the pressure drop is calculated
Air loses pressure as it moves through a hose. The loss grows quickly with flow and length and falls sharply as the bore gets bigger. This calculator uses a standard compressed air pipe-flow formula: drop (bar) = 450 × flow1.85 × length ÷ (diameter5 × absolute pressure), with flow in L/s free air, length in metres and diameter in mm.
Example: 60 CFM through 30 m of 3/4 inch (19 mm) hose at 100 psi drops about 0.3348 bar (4.856 psi).
Frequently asked questions
How much pressure drop is acceptable in an air hose?
Aim for under 0.5 bar (about 7 psi), and under 0.3 bar for tools that are sensitive to pressure such as blasting and impact tools.
What size air hose do I need?
Match the hose bore to the flow and length. As a guide, 3/8 inch suits small tools, 1/2 inch suits 25 to 40 CFM, 3/4 inch suits larger tools and longer runs, and 1 inch or more suits blasting and breakers.
Does a longer air hose reduce pressure?
Yes. Pressure drop increases in direct proportion to length, so doubling the hose length doubles the drop.
Does a bigger hose really make a difference?
A lot. Drop falls with the fifth power of diameter, so a slightly larger bore cuts the loss dramatically.
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