Compression Spring Rate Calculator
Estimate an ideal round-wire helical compression spring rate from active coils and mean coil diameter.
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Result
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Calculation steps
Work through one step at a time or reveal the complete calculation. The steps use your current inputs.
How to calculate
Use close-coiled elastic torsion of round wire with the mean coil diameter, not outside diameter.
k=G d⁴/(8 D³ active coils); force=k×deflection
Worked example
Wire 2 mm, mean diameter 20 mm, eight active coils and G=79 GPa give rate 2.46875 N/mm and load 24.6875 N at 10 mm compression.
Assumptions and input details
Mean diameter must be at least three wire diameters. Ideal small-deflection model; no solid height, end-coil inference, stress correction, buckling, fatigue or allowable load is determined.
References: Mid-West Spring: round-wire rate formula
Unit definitions
Unit selection is independent of language. Each selector contains only units for its physical quantity. Calculations use defined base units internally.
Choose from 23 length definitions, including explicitly labelled regional measures. Area conversions square the length factor; geometric volumes cube it.
Regional measures are not interchangeable merely because their names look similar. This is a documented selection, not a claim to include every historical unit.
NIST measurement tables · Japanese traditional units · Mainland China and Hong Kong unit distinctions
Using this calculator
Can I enter my own problem?
Yes. Replace the example values with your own inputs. The result, calculation steps, tables and applicable diagrams update from those inputs. Blank or invalid values clear the result; example values are never silently substituted for missing inputs.
Are the results exact?
Results use floating-point arithmetic and displayed rounding. Read the formula, assumptions and any stated data precision before interpreting the result.
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The calculation runs in your browser. No account, file upload or external AI service is required. Inputs are not saved between page reloads.
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