Lift Coefficient Calculator
Separating Airfoil Shape From Everything Else That Affects Lift
Lift force depends on speed, air density, wing area, and the airfoil's own aerodynamic shape and angle of attack all at once, which makes it hard to compare how "good" two different wing designs are directly. The lift coefficient factors out speed, density, and area, leaving a single dimensionless number that isolates how effectively a particular shape and angle of attack convert airflow into lift.
The Formula
L is lift force, ρ is air density (defaulting to 1.225 kg/m³, standard sea-level density, if not specified), v is velocity, and A is wing area.
Where This Calculation Matters
- Airfoil comparison — lift coefficient lets engineers compare the aerodynamic effectiveness of different airfoil shapes independent of the speed or size at which they were tested.
- Stall margin tracking — every airfoil has a maximum lift coefficient before flow separates and the wing stalls; monitoring Cₗ against that limit is central to stall-speed and safety-margin calculations.
- Wind tunnel data reduction — wind tunnel test results are reported as lift coefficients specifically so they generalize to full-scale aircraft at different speeds.
- Flap and high-lift device design — flaps and slats work by increasing the maximum achievable lift coefficient, allowing slower approach speeds without stalling.
Worked Examples
| Lift force | Velocity | Wing area | Cₗ |
|---|---|---|---|
| 5,000 N | 60 m/s | 20 m² | 0.113 |
| 2,000 N | 45 m/s | 15 m² | 0.108 |
These worked examples show cruise-condition lift coefficients; most conventional airfoils reach a maximum usable lift coefficient somewhere in the 1.2–1.8 range before stalling, higher with flaps deployed.
How to Use This Calculator
- Enter the lift force in newtons.
- Enter the velocity in m/s.
- Enter the wing area in square meters.
- Optionally enter air density in kg/m³ (defaults to 1.225, sea-level standard, if left blank).
- Select Calculate to get the lift coefficient.
Related Calculations
Compare against drag with the Drag Coefficient Calculator, or check whether the wing area supports the aircraft's weight with the Wing Loading Calculator.