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Lift Force & Flow Coefficient

Relate positive lift force to fluid density, flow speed, reference area and dimensionless lift coefficient.

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How to use this calculator

  1. Enter the known values in the units shown. Results update as you type.
  2. Where results are editable, change one to solve backwards. Lock a value to hold it fixed.
  3. Use the worked example to check the method. Reset restores the starting fields.

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Formula and method

Lift of 120 N at density 1.2 kg/m³, speed 10 m/s and reference area 2 m² corresponds to a lift coefficient of 1.

Lift coefficient = 2 × lift / (density × speed² × reference area)

Worked example

Enter these known values and leave the other values blank.

Positive lift force
120 N
Fluid density
1.2 kg/m³
Relative flow speed
10 m/s
Coefficient reference area
2 m²
Positive lift coefficient
1

Assumptions and limitations

  • This retained model accepts positive lift, coefficient, density, speed and area. Zero lift and negative lift are outside its supported domain.
  • Use the area convention associated with the coefficient, commonly wing planform area for aircraft wings. Wetted and planform areas are not interchangeable.
  • The coefficient depends on shape, angle of attack and flow conditions. This relation does not predict stall or make a coefficient transferable between different Reynolds or Mach numbers.

Common questions

Does the lift coefficient have units?

No. Consistent force, density, speed and area units cancel in the defining ratio.

Does this calculate angle of attack?

No. Finding angle of attack requires an appropriate lift curve or aerodynamic model for the relevant geometry and conditions.

References

The pound-force uses the exact international pound and standard gravity instead of the rounded captured factor. Bookify uses exact customary mass and volume definitions for density units, replacing rounded factors in the reference.

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