Ohm's Law & Power

Select an equation from the wheel to solve for a specific variable.

Volts Amps Power Ohms(Ω) E R P I E = P R E = P I E = I R R = E I R = E 2 P R = P I 2 I = P R I = P E I = E R P = E I P = I 2 R P = E 2 R

Reactance (X)

Calculate inductive or capacitive reactance for a given frequency.

Inductive Reactance

X_L = 2πfL

Inductive Reactance (XL):

0 Ω

Capacitive Reactance

X_C = 1 / (2πfC)

Capacitive Reactance (XC):

0 Ω

Parallel Tank (LC)

f0 = 1 / (2π√LC)

Resonant Frequency (f0):

0 Hz

Impedance at Resonance (XL ∥ XC):

0 Ω

Series Tank (LC)

f0 = 1 / (2π√LC)

Resonant Frequency (f0):

0 Hz

Impedance at Resonance (XL + XC):

0 Ω

Complex Impedance (RLC)

Calculate the complex impedance of R, L, and/or C combined in series or parallel at a given frequency. Leave a component blank to exclude it from the circuit.

Impedance (magnitude & phase):

0 Ω ∠ 0°

Impedance (rectangular, Z = R + jX):

0 + j0 Ω

Character:

—

XL = 0 Ω

XC = 0 Ω

PCB Trace Impedance

Single-ended characteristic impedance for microstrip and grounded coplanar waveguide (GCPW) PCB traces. These are quasi-static closed-form approximations — typically ±5–15% accuracy. Verify with a field solver (or your fab's stackup calculator) for critical designs.

Microstrip

IPC-2141: Z0 = (87/√(εr+1.41))·ln(5.98H / (0.8W+T))

Characteristic Impedance (Z0):

0 Ω

Grounded Coplanar Waveguide (GCPW)

Conformal-mapping model with Hilberg's elliptic-integral-ratio approximation

Characteristic Impedance (Z0):

0 Ω

Effective Dielectric Constant (εeff):

0

Free Space Path Loss (FSPL)

Calculate RF signal loss over distance in free space.

Path Loss:

0 dB

Resistor Divider

Calculate the output voltage of a voltage divider circuit, or solve for R1/R2 given a target output.

dBm / dBW Power Converter

Convert between RF power level (dBm/dBW) and Watts, and see the equivalent RMS voltage across a 50Ω or 75Ω load. Edit either the Power Level or Power field.

Voltage (RMS) @ 50Ω:

0 V

Voltage (RMS) @ 75Ω:

0 V

Wavelength / Frequency

Convert between frequency and free-space wavelength (λ = c / f). Edit either field.

RC Time Constant

Calculate the time constant and -3dB cutoff frequency of a resistor-capacitor network.

Time Constant (τ = RC):

0 s

Cutoff Frequency (fc = 1 / 2πRC):

0 Hz

VSWR / Return Loss

Convert between VSWR and Return Loss for an impedance mismatch. Edit either field.

Reflection Coefficient (Γ):

0

Antenna Designer

Calculate resonant dipole and monopole element lengths from free-space wavelength, adjusted by a velocity/end-effect factor.

Dipole (Half-Wave)

L = (c / 2f) × k

Total Length (tip to tip):

0 ft (0 m)

Each Leg (from center feedpoint):

0 ft (0 m)

Monopole (Quarter-Wave)

L = (c / 4f) × k

Element Length (base to tip):

0 ft (0 m)

Measured over an adequate ground plane / radial system.