Inputs
Results
Natural frequency f = (1/2π)√(k/m). Critical damping = 2√(km). Damping ratio ζ = c / critical.
What this calculator actually solves
Suspension natural frequency is the rate at which the car oscillates after a bump. Below ~1.0 Hz is soft and comfortable; above ~1.8 Hz is firm and "sporty." Knowing your ride frequency tells you whether the springs are matched to the weight — too soft and you bottom out; too stiff and you crash over bumps.
We also compute the damping ratio, which tells you how well the shocks are matched to the springs. Below 0.3 and the car oscillates; above 0.7 and the suspension feels harsh.
Who this is for
Hot-rodders and street tuners selecting springs for a specific feel.
Off-roaders and overlanders trying to match spring rate to bumper and winch additions that change corner weight.
How to read the results
Street comfort target is 1.0–1.4 Hz at ride height. Performance target is 1.6–2.2 Hz. Above 2.5 Hz, the suspension is racing-only — too harsh for street.
Damping ratio between 0.3 and 0.5 is the sweet spot. Above 0.6, the shocks are too stiff relative to the springs and the car will skip over bumps.
Limitations
This is a single-corner quarter-car model. Real suspension has pitch, roll, and anti-squat geometries that change the effective spring rate.
Shock damping is not constant — it's a function of velocity. The ratio we compute is the average at low velocity; it doesn't capture high-speed harshness.
Frequently Asked Questions
What's a "comfortable" ride frequency?
1.0–1.4 Hz for a luxury car, 1.4–1.7 Hz for a sports sedan, 1.7–2.2 Hz for a sports car. Above 2.5 Hz, expect harsh ride.
What if I add a heavy bumper or winch?
Corner weight changes, ride frequency drops proportionally to √(weight). You may need stiffer springs to restore ride quality.
My springs say 200 lbs/in — but my corner weight is 800 lbs. Is that right?
That's only 4" of total wheel travel before bottoming — which is why most race cars have very short travel and very stiff springs. For street use, you'd want springs that give 5–7" of total travel, which means a softer rate or a softer corner weight.
About this tool
What this tool is for: Suspension Frequency Calculator is a workbench reference for working mechanics, machinists, restoration shops, and serious hobbyists. It is built because the usual online calculators skip the friction loss, the sign convention, the unit conversion, or the engineering code that actually matters on the job.
Purpose and scope
Ride-rate to suspension frequency, plus a comfort-vs-performance read-out. It assumes a sprung/unsprung mass split you can refine with corner-weight measurements.
How to use the body of this page
The sections above this footer — “What this calculator solves,” “Who this is for,” “How to read the results,” and “Limitations” — describe in detail what the formula does, why a tech would use it, how to interpret the number, and where the model is wrong. The FAQ block answers the three or four questions most asked about this specific tool. Together they make up the “About” content for this page; you do not need to look elsewhere.
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All content on this page, including formulas and calculator outputs, is provided for general informational and educational purposes only. It is not professional engineering advice, it is not a substitute for manufacturer specifications, and it is not a warranty of fitness for any particular purpose.
Mechanical, hydraulic, and welding work can cause serious injury, death, or property damage if performed incorrectly. Numbers produced by this calculator reflect simplified textbook models; they do not capture manufacturing tolerances, material defects, environmental conditions, wear, fatigue, regulatory codes (such as ASME, DOT, or AWS), or the specific service conditions of your job. Always cross-check critical values against the original equipment manufacturer's published specifications and a qualified engineer's review before committing to the job.
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