Coaxial Cable Impedance Calculator
Estimate ideal coaxial characteristic impedance, propagation speed and capacitance/inductance per length.
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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 concentric perfect conductors filled uniformly by a nonmagnetic dielectric, in the quasi-TEM limit.
Z0≈60 ln(D/d)/√εr; C′=2πε0 εr/ln(D/d); L′=μ0 ln(D/d)/(2π)
Worked example
Diameter ratio 3 and relative permittivity 2.25 give impedance about 43.9444915 Ω and velocity factor 2/3.
Assumptions and input details
Outer inner-surface diameter must exceed the center conductor outside diameter. Uses rounded 60 Ω impedance constant and explicit SI ε0/μ0 approximations. Loss, skin effect, higher modes, tolerances and power ratings are excluded.
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.
Is my input uploaded?
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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