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Vehicle Ground Clearance Calculator

2026-09-27 6 min

Axle and frame clearance from tire diameter, stock frame height, lift and sag.

Axle (Diff) Clearance
15.5 in
Tire radius to diff
Frame Clearance
11.5 in
Loaded, lifted

Calculator

Tire Diameter(in) Help
in

True mounted diameter

Stock Frame Clearance(in)
in
Suspension Lift(in)
in
Load Sag(in) Help
in

Squat under trip load

Results update live as you type

Live statistics

Axle (Diff) Clearance

15.5 in

Tire radius to diff

Frame Clearance

11.5 in

Loaded, lifted

Results

Optimal

Axle (Diff) Clearance

15.5in

Tire radius to diff

Frame Clearance

11.5in

Loaded, lifted

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

Visualizations

Results overview

15.5Axle (Diff) Clearance
11.5Frame Clearance

Frame Clearance vs. Tire Diameter

Frame Clearance

11.5in
020

Formula

Separates what tires lift (everything, incl. diffs) from what suspension lifts (frame only).

Diff clearance ~= tire diameter / 2 - 1 in (pumpkin offset)

Alternative Form

Frame = stock + lift - sag (only tires lift the diffs)

Variables

SymbolNameUnitDescription
T/2Tire radiusinSets diff height

Explanation

Only bigger tires raise diff pumpkins — suspension lifts raise the frame while diffs stay put. Both matter off-road.

Step-by-Step Calculation

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

Step 1

Record the inputs.

Tire Diameter:33 in
Stock Frame Clearance:10 in
Suspension Lift:2 in
Load Sag:0.5 in
Result: 4 inputs ready
Step 2

Apply the formula.

Diff clearance ~= tire diameter / 2 - 1 in (pumpkin offset)
Result: Primary result = 11.5 in
Step 3

Read every derived output.

Axle (Diff) Clearance:15.5 in
Frame Clearance:11.5 in
Result: Frame Clearance = 11.5 in
Final Answer
15.5

Worked Examples

See how the calculator works with different scenarios.

Scenario

Overland SUV trip setup.

Inputs

Tires:33 in
Frame:10 in
Lift:2 in
Sag:0.5 in

Calculation

Diff = 15.5 in; frame = 11.5 in

Result

15.5-in diff, 11.5-in frame clearance.

Interpretation

Frame/skids are the limit — armor them.

Understanding Your Result

Your Result: Axle (Diff) Clearance: 15.5 in

What This Means

True clearance under load at the diffs and frame.

Why It Matters

Diffs snag rocks; frames high-center — know both numbers.

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

Clearance has two numbers: diffs and everything else.

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

  • •Measure loaded, not empty
  • •Armor the lowest frame points
  • •Air down for traction, not clearance

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.

Do lift kits increase ground clearance?
Frame clearance yes; diff clearance no — only taller tires raise pumpkins.
How much clearance do I need off-road?
Stock SUVs ~8 in handle dirt; 10-12+ with skids for real trails; 12+ for rock crawling.

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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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