Departure Angle Calculator

What Is Departure Angle?

The departure angle is the maximum angle your vehicle can descend without the rear bumper or hitch hitting the ground.

It is measured between:

• The ground surface
• An imaginary line from the rear tire contact point to the lowest rear point of the vehicle

In simple terms:

The shorter the rear overhang and the higher the rear clearance, the better your departure angle.

Why Departure Angle Is Important

A low departure angle can cause:

• Rear bumper damage
• Bent trailer hitches
• Stuck vehicles on steep drops
• Scraped spare tire mounts

A higher departure angle gives you:

• Better off-road performance
• Safer hill descents
• More confidence on trails
• Less damage risk

If you drive on dirt trails, rocky terrain, sand dunes, or steep inclines, this number matters.

How a Departure Angle Calculator Works

A Departure Angle Calculator uses geometry to calculate the angle based on your vehicle’s measurements.

Required Measurements

The calculator uses these inputs:

1. Rear Overhang Distance
   Distance from rear axle center to the furthest rear point.
2. Height of Lowest Rear Point
   Usually the bumper, hitch, or spare tire mount.
3. Ground Clearance at Rear Axle
   Clearance under the rear axle.
4. Tire Diameter
   Overall tire size including tread.
5. Measurement Unit
   Millimeters (mm) or inches.

Departure Angle Formula Explained

The calculator uses this formula:

Departure Angle = arctangent (Effective Height ÷ Rear Overhang)

Where:

Effective Height = Lowest Point Height − Ground Clearance

Then the result is converted from radians to degrees.

You do not need to do the math manually. The calculator handles it instantly. But understanding the logic helps you know what changes improve the result.

What Is a Good Departure Angle?

Here’s a general classification used in most calculators:

Typical Angles by Vehicle Type

• Sedan: ~12°
• Hatchback: ~15°
• SUV/Crossover: ~20°
• Traditional SUV: ~25°
• Pickup Truck: ~22°
• Mid-Range Off-Road: ~35°
• Extreme Off-Road: ~45°

If your result is under 20°, serious off-road use is not recommended.

How Vehicle Modifications Affect Departure Angle

The calculator also considers common modifications. Some help. Some hurt.

Modifications That Improve Departure Angle

• Lift Kit
  Raises the vehicle body and increases clearance.
• Larger Tires
  Increase overall vehicle height.
• High-Clearance Rear Bumper
  Reduces overhang and improves angle.

Modifications That Reduce Departure Angle

• Rear spare tire mount
• Trailer hitch
• Extended tow setup

These lower the rear-most point, reducing your effective angle.

If your calculator result is low, removing rear attachments is often the easiest fix.

How to Measure Your Vehicle Correctly

Accurate input gives accurate results.

Step 1: Measure Rear Overhang

Use a tape measure from the center of the rear axle to the furthest rear point.

Step 2: Measure Lowest Rear Point Height

Measure from ground to the lowest rear component.

Step 3: Measure Rear Axle Ground Clearance

Check directly under the rear axle.

Step 4: Confirm Tire Diameter

Use manufacturer specs or measure from ground to top of tire and double the radius.

Tip: Measure on flat ground for best accuracy.

Example Calculation

Let’s say:

• Rear Overhang: 900 mm
• Lowest Point Height: 400 mm
• Ground Clearance: 200 mm

Effective Height:

400 − 200 = 200 mm

Angle:

arctan(200 ÷ 900)

Result:

Approximately 12.5°

That would classify as Very Poor for off-road use.

This shows why many standard sedans struggle on steep trails.

When Should You Use a Departure Angle Calculator?

Use it when:

• Buying a new SUV or truck
• Planning off-road upgrades
• Installing a lift kit
• Adding larger tires
• Removing or installing a trailer hitch
• Comparing vehicle types

It helps you make decisions based on numbers instead of guesswork.

Departure Angle vs Other Off-Road Angles

Departure angle is just one part of off-road geometry.

Other important angles include:

• Approach Angle
• Breakover Angle

A complete off-road capability assessment includes all three.

Tips to Improve a Low Departure Angle

If your result is below 25°, consider:

1. Installing a lift kit
2. Upgrading to larger tires
3. Switching to a high-clearance bumper
4. Removing rear-mounted spare tire
5. Detaching trailer hitch when not needed

Even small changes can improve the angle by 3° to 8°.

Common Mistakes When Calculating Departure Angle

• Measuring from the wrong axle point
• Forgetting to subtract ground clearance
• Using incorrect tire diameter
• Measuring on uneven ground
• Confusing departure angle with approach angle

Accuracy matters.