Radio Formula Calculator

Calculate common radio formulas including Ohm's Law, resonance, wavelength, power, and more. Essential tool for amateur radio exam preparation.

Basic

• Ohm's Law: V = I × R
• Power (V × I): P = V × I
• Power (I²R): P = I² × R
• Power (V²/R): P = V² / R
• Potential Divider: Vout = Vin × R2 / (R1 + R2)

Capacitors

• Capacitive Reactance: Xc = 1 / (2πfC)
• Time Constant (CR): τ = C × R

Inductors

• Inductive Reactance: XL = 2πfL
• Time Constant (L/R): τ = L / R

AC / RF

• Impedance: Z = √(R² + X²)
• Resonant Frequency: f = 1 / (2π√LC)
• SWR (from voltages): SWR = (Vf + Vr) / (Vf - Vr)
• RMS Voltage: Vrms = Vpeak / √2

Transformers

• Transformer Voltage: Vs / Vp = Ns / Np
• Transformer Impedance: Zp / Zs = (Np / Ns)²

Decibels

• Gain (Power): Gain = 10 × log₁₀(Pout / Pin)
• Gain (Voltage): Gain = 20 × log₁₀(Vout / Vin)

Wavelength

• Wavelength: λ = c / f