Calculate suspension corner weight split, spring rate from sag, and ride frequency using corner weight, unsprung weight, motion ratio, and angle.

Per-corner, linear spring estimate using standard gravity. Sag calculations assume zero preload and constant geometry. Tire stiffness, damping, anti-roll bars and axle coupling are excluded; results are not vehicle setup or safety approval.

Suspension Weight Formula

The following relationship gives the suspension-supported (sprung) mass at one corner.

SW = CW - UW

Variables:

  • SW is the Suspension Weight (lb)
  • CW is the corner weight (lb) 
  • UW is the unsprung weight (lb) 

To calculate sprung mass at one corner, subtract unsprung mass from the corner scale reading. The widget treats lb, kg, g and oz as mass units and converts mass to force using standard gravity in the spring modes. Its linear sag and frequency estimates assume constant geometry, zero spring preload, and no tire or axle coupling. The nominal motion ratio excludes inclination; if a measured spring-travel/wheel-travel ratio already includes inclination, use angle 0ยฐ to avoid applying it twice.

How to Calculate Suspension Weight?

The following steps outline how to calculate the Suspension Weight.

  1. First, determine the corner weight (lb). 
  2. Next, determine the unsprung weight (lb). 
  3. Next, gather the formula from above = SW = CW – UW.
  4. Finally, calculate the Suspension Weight.
  5. After inserting the variables and calculating the result, check your answer with the calculator above.

Example Problem : 

Use the following variables as an example problem to test your knowledge.

corner weight (lb) = 1,500

unsprung weight (lb) = 500

SW = CW – UW = ?