Pneumatic cylinder air consumption and compressor size — L (ANR), per minute, required air flow

To size a compressor for pneumatic cylinders or estimate air cost, start with how much air a cylinder uses per stroke. SMC splits this into «air consumption» (for the compressor and running cost) and «required air volume» (for sizing valves, FRL units and piping). This guide follows the formulas and example in SMC's «Best Pneumatics» Technical Data 2.

Air used by one stroke of the cylinder

qc (L ANR) = A (mm²) × L (mm) × (P + 0.1) ÷ 0.1 × 10⁻⁶
  A  area — extend πD²/4, retract π(D² − d²)/4
  L  stroke,  P  operating pressure (MPa, gauge)

ø50 / rod 20, 600 mm stroke, 0.5 MPa:
  extend   1963.5 × 600 × 6 × 10⁻⁶ = 7.07 L
  retract  1649.3 × 600 × 6 × 10⁻⁶ = 5.94 L
  one cycle (out and back)        = 13.0 L (ANR)

(P + 0.1) ÷ 0.1 turns gauge pressure into an absolute pressure ratio against atmosphere (about 0.1 MPa). A cylinder volume filled at 0.5 MPa becomes six times that volume at atmospheric pressure. ANR means volume converted to standard atmospheric conditions, so it compares directly with a compressor's delivery.

Tubing — matters more for small cylinders

qp (L ANR) = a (mm²) × l (mm) × P ÷ 0.1 × 10⁻⁶       (a inside area, l length)

6 mm ID tube (28.3 mm²), 2 m, 0.5 MPa:  28.3 × 2000 × 5 × 10⁻⁶ = 0.28 L  (0.57 L out and back)

Each time the valve switches, the tubing between valve and cylinder is filled and exhausted too. In the example above tubing is about 4 %, but a ø16 cylinder with a 50 mm stroke on 1 m of 4 mm ID tube uses 0.24 L per cycle, of which 0.13 L is tubing — more than half. Mounting the valve close to small cylinders saves air. (SMC's formula uses P ÷ 0.1 for tubing and (P + 0.1) ÷ 0.1 for the cylinder; it is reproduced as published.)

Per-minute consumption and the compressor — SMC's example

Ten ø50 cylinders, 600 mm stroke, 0.5 MPa, 5 cycles/min, 2 m of 6 mm ID tube to the valve

Cylinder per cycle   13 L (ANR)      (SMC graph; 13.0 by formula)
Tubing per cycle     0.56 L (ANR)    (0.565 by formula)
Total  (13 + 0.56) × 10 × 5 = 678 L/min (ANR)
Compressor          at least × 1.4  ≈ 950 L/min (ANR)

SMC says to choose a compressor with delivery well above the calculated total, allowing for temperature drop, leakage and intermediate equipment, and gives «at least 1.4 times» as a reference. Add continuous users such as air blow-off and vacuum ejectors on top of the cylinders.

Dropping the pressure by 0.1 MPa cuts consumption by about 17 %. If the cylinder has force to spare, setting the regulator only as high as needed is the simplest way to save air (check force with the load factor in the «Pneumatic cylinder force» guide).

Required air flow — valves, FRL and upstream piping

Q (L/min ANR) = (qc + qp) × 60 ÷ t      (t time per stroke, s)
Use the larger of extend and retract

ø50/20, 600 mm, 0.5 MPa, extending in 1 s:  (7.07 + 0.28) × 60 ÷ 1 = 441 L/min (ANR)

If air consumption is a per-minute average, required air volume is the flow at the moment of movement. The same cylinder needs more the faster it moves, and when several move at once their sum must pass through the valves, filter, regulator and upstream piping. Sizing piping on the average alone lets pressure sag when cylinders move together.

In PortDock

• «Pneumatic Cylinder Air Consumption Calculator» web tool: bore, rod, stroke, pressure (MPa, bar, kgf/cm², psi), double/single acting and tubing → per-cycle and per-minute consumption, compressor guide (× 1.4) and required air flow. The defaults are SMC's example.
• «Pneumatic Cylinder Force Calculator» web tool: the force at the same pressure — see how far the pressure can come down.
• Serial Plotter and Modbus Master: log a supply pressure sensor or flow meter (analog → Modbus) to see how far pressure drops when several cylinders move together.

Published 2026-10-24