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Automotive Calculators

Turning Radius Calculator

2026-09-27 6 min

Curb-to-curb turning radius from wheelbase and max steering angle.

Turning Radius
14.3 ft
To outer front tire
Turning Circle
28.6 ft
Curb to curb diameter

Calculator

Wheelbase(in) Help
in

Axle to axle

Max Steering Angle(deg) Help
deg

Inner wheel lock angle

Results update live as you type

Live statistics

Turning Radius

14.3 ft

To outer front tire

Turning Circle

28.6 ft

Curb to curb diameter

Results

Optimal

Turning Radius

14.3ft

To outer front tire

Turning Circle

28.6ft

Curb to curb diameter

Planning estimate from standard automotive formulas. Validate with dyno, timeslip or datalog data when precision matters.

Visualizations

Results overview

14.3Turning Radius
28.6Turning Circle

Turning Radius vs. Wheelbase

Turning Radius

14.3ft
040

Formula

Ackermann-style single-track geometry: wheelbase sets the lever, lock angle sets the arc.

Radius = wheelbase / tan(steer angle)

Alternative Form

Bicycle-model geometry to the outer front tire path

Variables

SymbolNameUnitDescription
WBWheelbaseftLonger = wider arc
deltaSteer angledegMore lock = tighter

Explanation

Long trucks U-turn in 45+ ft while Minis spin in 35 — wheelbase and lock angle are the whole story.

Step-by-Step Calculation

Follow each step to understand how the result is calculated from your inputs.

Step 1

Record the inputs.

Wheelbase:120 in
Max Steering Angle:35 deg
Result: 2 inputs ready
Step 2

Apply the formula.

Radius = wheelbase / tan(steer angle)
Result: Primary result = 14.3 ft
Step 3

Read every derived output.

Turning Radius:14.3 ft
Turning Circle:28.6 ft
Result: Turning Radius = 14.3 ft
Final Answer
14.3

Worked Examples

See how the calculator works with different scenarios.

Scenario

Full-size SUV U-turn.

Inputs

WB:120 in
Lock:35 deg

Calculation

10 / tan(35) = 14.3 ft radius, 28.6-ft circle

Result

~29-ft turning circle.

Interpretation

Needs a wide street or a 3-point turn on narrow ones.

Understanding Your Result

Your Result: Turning Radius: 14.3 ft

What This Means

Tightest circle the vehicle can drive.

Why It Matters

U-turns, parking structures, driveways and trail switchbacks all ask this question.

Professional Interpretation

Treat the primary result as a planning estimate, then validate on a dyno, at the track, or with logged sensor data. If measured numbers disagree by more than ~10%, re-check inputs (units are the usual culprit) before changing parts.

Recommendations

  • •Double-check units on every input before trusting the result
  • •Compare against the worked example below to sanity-check magnitude
  • •Validate with measured data (dyno, timeslip, datalog) when it matters

Learn — fuel economy, deeply

Turning radius is wheelbase versus steering lock.

1 · Where the gallon goes (energy path)

Engine heat

60–70% lost

Coolant + exhaust carry most energy away. Hybrids recover some via Atkinson cycle + regen.

Driveline

5–15% lost

Transmission, differential, accessories. CVTs and 8–10 speed autos lose less.

Aero drag

∝ v²

Doubles from 55→78 mph. Roof boxes hurt more than trunks.

Rolling + brakes

10–20%

Tires, weight, stops. Regen braking (hybrid/EV) reclaims city braking energy.

4 · Measure like a pro (the 3-tank protocol)

  1. Fill to first click at the same pump, record the odometer (Tank 0).
  2. Drive normally for 2–3 tanks; always refill to first click at the same pump.
  3. MPG = total miles ÷ total gallons across all tanks — averaging kills pump-click noise.
  4. Cross-check with the trip computer; a persistent >10% gap means the computer needs calibration — or the car needs service.
  5. Log with an OBD-II dongle for per-trip MPG if you want to isolate commute vs. highway behavior.

Practical Tips

  • •Know your circle before tight trails
  • •Trailers pivot behind — plan wider
  • •Rear-steer options transform big trucks

Common Mistakes

Mixing units (inches with mm, psi with kPa)
Convert every input to the unit shown on its field before calculating.
Trusting a single output blindly
Cross-check with the worked example and, when it matters, a dyno or datalog.

Assumptions

This calculator makes the following assumptions to provide estimates:

Steady-state model: Formulas assume stabilized conditions; transients, heat soak and traction limits are excluded.
Standard factors: Empirical constants (BSFC, VE, drivetrain loss) use typical values — your combination may differ.

Limitations

Be aware of these limitations when using this calculator:

Estimate, not measurement: Predictions carry real-world scatter of roughly ±5–15% depending on the model.
No transient effects: Shift time, wheelspin, spool lag and heat soak are not modeled here.

Frequently Asked Questions

Answers to common questions about this calculator.

What is a good turning circle?
Cars 34-38 ft; SUVs 38-42; long trucks 44-50+. Smaller is friendlier everywhere but the highway.
Do 4-wheel steering or rear steer help?
Dramatically — counter-phase rear steer can cut circles 10-20% (Hummer crab, Sierra Denali).

Related Calculators

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Related Guides

Deepen your understanding with these educational resources.

Glossary

Technical terms used in mortgage calculations explained in plain language.

MPG
Miles per gallon. Distance travelled per gallon of fuel; higher is better. US gallon = 3.785 L.
L/100 km
Litres consumed per 100 kilometres; lower is better. Standard metric efficiency unit.
MPGe
Miles per gallon-equivalent. EV metric: miles travelled on 33.7 kWh (energy of 1 gal of gasoline).
CAFE
Corporate Average Fuel Economy — US fleet-average efficiency standard enforced by NHTSA.
Rolling resistance
Energy lost deforming tires as they roll. Low-pressure or wide tires raise it.
Aerodynamic drag
Air resistance growing with the square of speed — why highway MPG falls fast above 60 mph.
Hypermiling
Driving techniques (coasting, steady speed, anticipation) that maximise real-world MPG.
OBD-II
On-board diagnostics port. Scanners and dongles read live MPG, fuel trim and fault codes.

Authoritative References

Trusted sources and standards referenced by this calculator.

Applicable Standards

EPA Fuel Economy Testing (40 CFR Part 600)CAFE — Corporate Average Fuel Economy Standards (NHTSA)WLTP — Worldwide Harmonised Light Vehicle Test ProcedureSAE J1321 / J1711 — Fuel consumption test proceduresISO 2575 — Road vehicles symbols & efficiency markings

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