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Shock Damping Calculator

2026-09-27 6 min

Critical damping and recommended sport/comfort settings from sprung weight and wheel rate.

Critical Damping
49.9 lb-s/in
Sport Setting (65%)
32.4 lb-s/in
Comfort Setting (30%)
15.0 lb-s/in

Calculator

Sprung Corner Weight(lb)
lb
Wheel Rate(lb/in)
lb/in
Results update live as you type

Live statistics

Critical Damping

49.9 lb-s/in

Sport Setting (65%)

32.4 lb-s/in

Comfort Setting (30%)

15.0 lb-s/in

Results

Optimal

Critical Damping

49.9lb-s/in

Sport Setting (65%)

32.4lb-s/in

Comfort Setting (30%)

15.0lb-s/in

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

Visualizations

Results overview

49.9Critical Damping
32.4Sport Setting
15Comfort Setting

Sport Setting (65%) vs. Sprung Corner Weight

Sport Setting (65%)

32.4lb-s/in
0120

Formula

Textbook critical damping for the corner, with usable zeta bands for sport and comfort valving.

Critical = 2 x sqrt(rate x mass), mass = W/386

Alternative Form

Street rebound typically 50-70% of critical; comfort 25-35%

Variables

SymbolNameUnitDescription
CcCriticallb-s/inNo-overshoot threshold
zetaDamping ratioActual/critical

Explanation

Damping ratio (zeta) is the tune: ~0.2 comfort, ~0.5-0.7 sport, ~0.7+ race — all relative to critical.

Step-by-Step Calculation

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

Step 1

Record the inputs.

Sprung Corner Weight:800 lb
Wheel Rate:300 lb/in
Result: 2 inputs ready
Step 2

Apply the formula.

Critical = 2 x sqrt(rate x mass), mass = W/386
Result: Primary result = 32.4 lb-s/in
Step 3

Read every derived output.

Critical Damping:49.9 lb-s/in
Sport Setting (65%):32.4 lb-s/in
Comfort Setting (30%):15.0 lb-s/in
Result: Sport Setting (65%) = 32.4 lb-s/in
Final Answer
49.9

Worked Examples

See how the calculator works with different scenarios.

Scenario

Baseline valving for a sport setup.

Inputs

Weight:800 lb
Rate:300 lb/in

Calculation

Cc = 2 x sqrt(300 x 2.073) = 49.9 lb-s/in

Result

Critical ~50; sport ~32; comfort ~15 lb-s/in.

Interpretation

Hand these to the shock builder as low-speed targets.

Understanding Your Result

Your Result: Critical Damping: 49.9 lb-s/in

What This Means

Damper force-per-velocity targets for the corner.

Why It Matters

Gives shock builders and clicker knobs a physics baseline instead of guesses.

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

Damping is force opposing velocity, sized to the corner.

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

  • •Revalve when changing springs 20%+
  • •Adjust rebound first
  • •Log settings with lap/seat feedback

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.

What damping ratio should I run?
Street 0.25-0.4, sport 0.5-0.65, race 0.65-0.9+. More spring needs proportionally more damping.
Rebound or compression?
Rebound controls the sprung mass (most of the feel); compression tunes bump absorption and platform.

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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.
Damping ratio
Actual damping over critical — the universal shock-tune number.

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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