Cross Weight Calculator

What Is Cross Weight?

Cross weight is the percentage of total vehicle weight carried on one diagonal of the car.

It is calculated using:

• Left Front (LF)
• Right Front (RF)
• Left Rear (LR)
• Right Rear (RR)

The key diagonal is:

Left Front + Right Rear

Then divide that by total vehicle weight.

Cross Weight Formula

Cross Weight % = (LF + RR) ÷ Total Weight × 100

If the result is:

• 50% → Perfectly balanced diagonally
• Above 50% → More weight on LF/RR diagonal (adds wedge)
• Below 50% → More weight on RF/LR diagonal

Many racers call cross weight wedge.

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Why Cross Weight Matters

Cross weight affects:

• Corner entry balance
• Corner exit traction
• Left vs right turn handling
• Launch stability (drag racing)
• Steering feel

A small 1–2% change can completely change how the car behaves.

For example:

• Too much cross weight → car may feel tight
• Too little cross weight → car may feel loose

Balance is everything.

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How the Cross Weight Calculator Works

The calculator uses these inputs:

• Left Front Scale (lbs)
• Right Front Scale (lbs)
• Left Rear Scale (lbs)
• Right Rear Scale (lbs)
• Driver weight (with helmet and gear)
• Fuel load (6 lbs per gallon)
• Vehicle type
• Target cross weight percentage

It then calculates:

• Total vehicle weight
• Left side percentage
• Front / rear percentage
• Cross weight percentage
• Wedge (Cross − 50%)
• Bite (LR − RR)
• Adjustment recommendations

This gives you both numbers and setup guidance.

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Step-By-Step: How to Use a Cross Weight Calculator

1. Put the Car on Scales

Use four corner scales on a level surface.

Make sure:

• Tire pressures are set
• Driver is in the seat (or equal ballast added)
• Fuel level matches race condition
• Suspension is settled

2. Enter the Four Corner Weights

Input:

• LF
• RF
• LR
• RR

All four must be entered to calculate correctly.

3. Add Driver and Fuel

Fuel matters more than most people think.

12 gallons adds 72 lbs. That changes balance.

Always scale the car in race trim.

4. Choose Vehicle Type

The calculator adjusts recommendations depending on:

• Circle track
• Drag racing
• Road course
• Street/strip
• Dirt oval

Each style needs a different cross weight target.

5. Set Target Cross Weight

Common targets:

Application	Target Cross Weight
Road course	49.5–50.5%
Drag racing	50–51%
Asphalt circle track	52–56%
Dirt oval	52–58%
Street/strip	50–52%

The calculator compares your current setup to your target and shows how far off you are.

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Understanding the Results

Cross Weight Percentage

This is your diagonal balance number.

Example:

If total weight = 3,200 lbs
LF + RR = 1,664 lbs

Cross Weight =
1,664 ÷ 3,200 × 100 = 52%

That means you have 2% wedge.

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Wedge (Cross − 50%)

• 0% → Neutral
• Positive number → Adds tightness
• Negative number → Adds looseness

Small changes matter. Even 0.5% can be noticeable.

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Bite (Left Rear − Right Rear)

Bite is important for:

• Dirt racing
• Drag racing
• Low grip conditions

More left rear weight usually improves forward traction.

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How to Adjust Cross Weight

The calculator suggests three types of changes:

1. Spring or Coil Adjustments

To increase cross weight:

• Raise LF and RR
  or
• Lower RF and LR

To decrease cross weight:

• Lower LF and RR
  or
• Raise RF and LR

Small changes go a long way.

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2. Sway Bar Changes

• Stiffen rear bar → increases rotation
• Stiffen front bar → increases tightness

The calculator estimates approximate stiffness changes in lbs/in.

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3. Moving Ballast

Sometimes the easiest solution is weight placement.

If cross weight is low:

Move weight from RF/LR diagonal to LF/RR diagonal.

Even 20–30 lbs can make a big difference.

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Application-Specific Guidance

Circle Track (Asphalt)

• Typical: 52–56%
• Higher cross → tighter entry
• Lower cross → freer rotation

Left-turn cars need preload for consistent cornering.

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Dirt Oval

• 52–58% common
• Higher cross helps on slick tracks
• Bite (LR weight) is critical

Track condition changes everything.

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Drag Racing

• 50–51% ideal
• Too much wedge can cause drift
• More bite helps launch on marginal surfaces

Launch straight and repeatable is the goal.

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Road Course / Autocross

• 49.5–50.5%
• Neutral balance for left and right turns
• Adjust slightly for track direction dominance

Balance beats bias here.

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Street / Strip

• 50–52% works well
• Slight wedge improves stability
• Comfort and predictability matter more than ultimate edge grip

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Common Cross Weight Mistakes

1. Scaling without driver weight
2. Ignoring fuel load
3. Making large adjustments
4. Not re-settling suspension before re-scaling
5. Chasing cross weight without checking tire temps

Numbers guide you, but driver feel confirms it.

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Example Calculation

Let’s say:

• LF: 850 lbs
• RF: 825 lbs
• LR: 780 lbs
• RR: 795 lbs
• Driver: 180 lbs
• Fuel: 12 gallons

Fuel weight = 12 × 6 = 72 lbs

Total weight = 850 + 825 + 780 + 795 + 180 + 72
Total = 3,502 lbs

Cross diagonal (LF + RR) = 850 + 795 = 1,645 lbs

Cross weight =
1,645 ÷ 3,502 × 100 = 46.97%

That is low for circle track. The car may feel loose.

The calculator would suggest increasing wedge.

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When to Recheck Cross Weight

• After spring changes
• After sway bar changes
• After ride height changes
• After moving ballast
• After major suspension work

Cross weight is not set once and forgotten.