How to use this calculator
- Enter wheelbase and track. Use front track width measured at tire centerlines.
- Enter inside angle. Use the inside front tire angle at the steering position.
- Enter outside angle. Use the measured outside front tire angle.
- Read Ackermann. Compare actual geometry with the pure Ackermann target.
How it works
Pure Ackermann satisfies the relationship: cot(outside) - cot(inside) = track / wheelbase. The calculator reports actual percentage against that target.
Use this with lateral acceleration and tire contact patch screens when evaluating chassis setup.
Worked example
Verified against the live calculator
With a 2,700 mm wheelbase, 1,580 mm track and 30 degree inside angle, pure Ackermann calls for about 24.3 degrees at the outside tire.
Frequently asked questions
What is Ackermann steering percentage?
It compares the actual inside/outside steer-angle relationship with the ideal relationship where both front tires point toward the same turn center.
How do you calculate ideal outside steer angle?
Use wheelbase, track width and inside steer angle to find the turn center, then solve the outside wheel angle.
Is 100 percent Ackermann always best?
No. Tire slip angles, compliance and vehicle use can make less or more than pure Ackermann desirable.
What does outside angle error mean?
It is actual outside steer angle minus the ideal outside angle at the entered inside angle.
Method & assumptions
- Uses planar steering geometry at one steering position.
- Does not model tire slip angle, caster, KPI, compliance steer, bump steer or steering rack travel.