Spring Rate Calculator
Ride frequency → wheel rate → spring rate
Vehicle Parameters
Enter car weight, weight distribution, unsprung masses and motion ratios. All results update automatically.
Guide: 35–55 kg (hub, brake, lower arm, half-wheel)
Guide: 50–60 kg (hub, brake, axle, half-wheel)
MR > 1 = mechanical advantage (spring stiffer than wheel rate)
Target Ride Frequency
Rear is typically set 5–15% higher than front to resist pitch oscillation on corner entry and promote mild understeer balance.
| Vehicle type | Frequency range |
|---|---|
| Low performance street | 0.5 – 1.0 Hz |
| High performance street | 1.0 – 1.5 Hz |
| Rally | 1.0 – 2.0 Hz |
| Low downforce circuit | 1.5 – 2.5 Hz |
| Med downforce circuit | 2.0 – 3.5 Hz |
| High downforce circuit | 3.5 – 5.0 Hz |
Results
⚠️ Sprung mass is negative or zero at one or more corners. Unsprung weight exceeds per-corner axle load — check your inputs.
Sprung mass per corner
Front
—kg
Rear
—kg
Installation ratio (1 ÷ Motion Ratio)
Front
—
Rear
—
Wheel rate
Front
—N/mm
Rear
—N/mm
Spring rate (at spring)
Front
—N/mm
—
kg/mm
—
lb/in
Rear
—N/mm
—
kg/mm
—
lb/in
Static compression at ride height
Front
—mm
—
spring (mm)
Rear
—mm
—
spring (mm)
Frequency verification
Front
—Hz
Rear
—Hz
Frequency balance (rear ÷ front)
Ratio
—
Difference
—Hz
Formulas ▶ show
💡 Static linear model — does not account for aero load, bump stop engagement, or ARB contribution to wheel rate. For high-downforce setups, consider calculating at both low-speed and high-speed aero loads and selecting a compromise spring.
Reverse — Current Frequency from Spring Rate
Enter only the values you want to override — any field left empty falls back to the main inputs above. Useful for testing different fuel loads, ballast or spring sets without re-entering everything.
Implied ride frequency
Front
—Hz
Rear
—Hz
Implied wheel rate
Front
—N/mm
Rear
—N/mm
Frequency balance (rear ÷ front)
Ratio
—
Difference
—Hz