Psi to CFH Conversion: Pressure and Airflow Explained

There is no single conversion from psi to cfh: psi measures pressure, while cfh measures gas flow, so pressure alone cannot determine a flow rate. A psi-to-cfh calculator needs additional information such as the gas, pipe or opening size, temperature, upstream and downstream pressures, and flow conditions; enter those in a suitable flow model or use a measured flow value.

Formula

This calculator converts each input to another unit of the same kind. It does not calculate airflow from pressure. Pressure in pascals = pressure in pounds per square inch × 6,894.757293. Flow in cubic metres per hour = flow in cubic feet per hour × 0.0283168466. Here, psi is pressure in pounds per square inch (lbf/in²), Pa is pascals, cfh is volumetric flow in cubic feet per hour, and m³/h is cubic metres per hour.

The conversion factors follow from the definitions of the units: one inch is exactly 0.0254 metres, and one foot is exactly 0.3048 metres. Thus one square inch is 0.00064516 m², so one psi is about 6,894.76 Pa. One cubic foot is 0.0283168466 m³. These are unit conversions, not a physical relationship between pressure and flow.

Worked Example

With the calculator’s default inputs, pressure is 10 psi and flow is 100 ft³/h.

• Pressure: 10 psi × 6,894.757293 = 68,947.57293 Pa, which rounds to 68,948 Pa.
• Flow: 100 ft³/h × 0.0283168466 = 2.83168466 m³/h, which rounds to 2.83 m³/h.

The two results describe separate input quantities. The pressure result does not imply that the flow is 100 ft³/h; that flow was entered independently.

Why Pressure Alone Cannot Give CFH

Pressure is a measure of force distributed over an area. Flow rate describes how much gas volume passes a point per unit time. In a pipe or valve, pressure difference can drive flow, but the resulting rate also depends on resistance and gas properties. A large, unobstructed opening and a narrow, restrictive passage can have very different flow rates at the same pressure difference.

For a gas, the meaning of a pressure reading also matters. Gauge pressure (psig) is measured relative to local atmospheric pressure; absolute pressure (psia) is measured from a vacuum. Many gas-flow equations require absolute pressure, and often the pressure difference across the restriction as well. A gauge reading on the upstream side alone may not provide either quantity.

Flow may be stated as actual cubic feet per hour at the conditions in the pipe, or as standard cubic feet per hour (SCFH) referenced to specified temperature and pressure conditions. The reference conditions vary by convention, so “standard” should be defined in the equipment documentation or applicable specification. Actual and standard volumetric flow figures are not automatically interchangeable.

What a Real Flow Calculation Needs

To estimate flow through a particular system, identify the physical path and the conditions, then choose an equation or manufacturer’s flow data that matches them. Depending on the setup, useful inputs can include:

• Gas identity or composition, because density and compressibility vary between gases.
• Upstream and downstream absolute pressures, not just one pressure reading.
• Gas temperature and, where relevant, humidity or other composition details.
• Pipe inside diameter, length, fittings, and surface or restriction characteristics.
• The type and geometry of the valve, orifice, regulator, or other flow-limiting component.
• Whether flow is steady, whether the gas is compressible under the conditions, and whether the flow may be choked.

For a known component, its documented flow coefficient or a tested flow curve can be more useful than a generic pipe equation. Such data is specific to the component and its stated conditions; do not assume that a coefficient or chart for one device applies to another.

How to Use the Unit Converter

Use the block above to convert pressure and flow only when you already have those quantities. Enter the pressure in psi to read its pascal equivalent, and enter the flow in cfh to read its m³/h equivalent. The inputs are independent: changing one does not calculate or alter the other physical quantity.

To convert the flow result back, divide m³/h by 0.0283168466 to obtain ft³/h. For a quick check, 1,000 cfh is about 28.32 m³/h. For pressure, 1 psi is about 6.895 kPa, and 100 kPa is about 14.50 psi. The calculator rounds its displayed outputs, so use unrounded values for intermediate calculations when precision matters.

Common Conversion Mistakes and Limits

• Treating psi as a flow unit: psi cannot be directly converted to cfh. A result requires a flow model or a flow measurement.
• Mixing gauge and absolute pressure: check whether a formula expects psig or psia. They are not equal; absolute pressure includes atmospheric pressure.
• Ignoring the pressure drop: flow is generally driven by a difference in pressure, not simply the upstream pressure value.
• Mixing actual and standard flow: state the reference conditions whenever reporting SCFH or comparing values from different sources.
• Rounding too early: keep extra digits during calculations and round the final answer to a precision supported by the measurement.

This page’s calculator performs exact-factor unit arithmetic to the displayed precision; it does not estimate a device’s capacity, certify a system, or account for measurement uncertainty. For selecting, operating, or checking gas equipment, use the relevant technical documentation and have a qualified professional assess the system where required. A pressure-to-flow estimate should not be treated as a safety rating.

Frequently Asked Questions

How many cfh is 1 psi?
There is no universal cfh value for 1 psi. Pressure and flow are different quantities, and flow depends on the gas, pressure difference, temperature, and restrictions in the path.

Can I convert psi directly to cubic feet per hour?
No. You can convert psi to another pressure unit, or cfh to another flow unit, but converting between pressure and flow requires additional system information and an appropriate flow equation or measured data.

What is 1 cfh in m³/h?
One cubic foot per hour is approximately 0.02831685 m³/h. Conversely, 1 m³/h is approximately 35.3147 cfh.

Is psi the same as psig?
Not necessarily. “Psi” may be used informally, while psig explicitly means gauge pressure relative to the surrounding atmosphere. Psia means absolute pressure. Check the instrument and formula conventions.

What does SCFH mean?
SCFH means standard cubic feet per hour: a gas flow expressed at defined reference conditions. Since conventions can use different reference conditions, confirm the temperature and pressure behind a stated SCFH value.

Related

• Water Heating Energy Calculator
• Atmospheric Pressure from Elevation and Temperature
• Ice to Water Conversion Calculator and Melting Formula

in psi | Pressure | psi | 10 | 0
in cfh | Flow | ft³/h | 100 | 0
out pressure_pa | Pressure equivalent | Pa | psi * 6894.757293 | 0
out flow_m3h | Flow equivalent | m³/h | cfh * 0.0283168466 | 2