HVAC fan-curve pressure interpolation calculator

Calculate interpolated fan pressure with your own figures.

Your numbers

Use the units shown. Results update as you change valid inputs.

Use interpolated fan pressure to compare changes to your inputs. The method and limits below explain the scope.

Examples

Examples

Try the starting example

Measured airflow points (m³/s)
0.5,1,1.5
Measured pressure points (Pa)
500,400,200
Requested airflow (m³/s)
0.8
Interpolated fan pressure (Pa)
440

Try another scenario

Measured airflow points (m³/s)
[0.55, 1, 1.5]
Measured pressure points (Pa)
[500, 400, 200]
Requested airflow (m³/s)
0.8
Interpolated fan pressure (Pa)
444.444444
Calculation method

Calculation method

Interpolated fan pressure (Pa)

Piecewise-linear interpolation between increasing measured airflow points; extrapolation rejected.

Symbols and units
a
Measured airflow points (m³/s)
b
Measured pressure points (Pa)
c
Requested airflow (m³/s)

Use the units shown. A list keeps the order in which you enter its values. The symbol ^ means “raised to the power of”.

Assumptions & limits

Assumptions & limits

  • User-supplied measurements and assumptions; Piecewise-linear interpolation between increasing measured airflow points; extrapolation rejected. Supported limits: Finite numeric values bounded to 1e9 magnitude; lists and tables contain 1–100 records unless a stricter bound is stated. Inputs use the units shown. Lists explicitly paired by a method must have matching lengths; independent polynomial coefficient vectors may differ. Respect stated physical, interpolation, policy and computational domain limits.
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