RF & Microwave Calculators
26 free calculators with formulas and worked examples.
Calculate VSWR, return loss, skin depth, noise figure, Smith chart impedance matching, link budgets, and more for RF and microwave circuits from MHz to mmWave.
Microstrip Impedance
Calculate microstrip impedance using Hammerstad-Jensen equations. Get Z0, effective dielectric constant, and propagation delay for PCB trace design. Free, instant results.
Link Budget
Free RF link budget calculator: enter Tx power, antenna gains, frequency, and distance to get received signal level, link margin, and max range. Covers satellite, terrestrial, and IoT links.
VSWR / Return Loss
Convert between VSWR, return loss, reflection coefficient, and mismatch loss instantly. Get reflected and transmitted power percentages. Free, instant results.
dBm Converter
Convert dBm to watts, milliwatts, dBW, dBuV, and Vrms instantly. Enter power level and impedance for all RF power unit conversions. Free, instant results.
Cascaded NF
Calculate cascaded noise figure and IP3 for multi-stage RF receiver chains using the Friis formula. Optimize LNA and filter ordering. Free, instant results.
Skin Depth
Calculate skin depth and surface resistance for copper, aluminum, and other conductors at any frequency. Essential for RF shielding and PCB design. Free, instant results.
Wavelength / Frequency
Convert between frequency, wavelength, and wavenumber in free space or any dielectric. Calculate half-wave and quarter-wave lengths for antenna design. Free, instant results.
Coax Impedance
Calculate coaxial cable characteristic impedance (Z0), capacitance, inductance per meter, and TE11 cutoff frequency from conductor dimensions. Free, instant results.
Coax Loss
Calculate RF cable attenuation for LMR-400, RG-58, RG-213, and more. Enter cable type, frequency, and length to get insertion loss in dB. Free, instant results.
ISM Coexistence
Analyze collision probability and throughput impact when WiFi, Bluetooth, Zigbee, or LoRa share ISM bands. Enter duty cycles and channels. Free, instant results.
Attenuator Designer
Design Pi and T attenuator pads with exact resistor values and nearest E24 matches. Enter attenuation and impedance for both topologies. Free, instant results.
Smith Chart
Free interactive online Smith Chart tool — plot impedance, calculate VSWR, return loss, and reflection coefficient instantly. Real-time updates, load presets, and shareable URLs.
Q Factor
Calculate quality factor (Q) for inductors and capacitors from ESR and frequency. Determine resonant bandwidth and half-power frequencies. Free, instant results.
Waveguide
Calculate rectangular waveguide cutoff frequencies for TE and TM modes, guide wavelength, and phase/group velocity. Enter dimensions and mode numbers. Free, instant results.
Free-Space Path Loss
Calculate free-space path loss (FSPL) in dB using the Friis equation. Enter frequency and distance for wireless link budget analysis. Free, instant results.
Radar Range
Calculate maximum radar detection range from peak power, antenna gain, RCS, noise figure, and bandwidth using the radar equation. Free, instant results.
PA Efficiency
Calculate RF power amplifier PAE, drain efficiency, gain, and heat dissipation from Pout, Pin, and DC bias. Essential for PA design. Free, instant results.
IMD / IP3
Calculate IIP3, OIP3, IM3/IM2 products, and spurious-free dynamic range for RF amplifiers and mixers. Analyze two-tone spur frequencies. Free, instant results.
Phase Noise to Jitter
Convert oscillator phase noise (dBc/Hz) to RMS jitter in ps and ADC SNR limit. Integrate over offset frequency range for clock design. Free, instant results.
Vibration Phase Noise
Calculate vibration-induced phase noise for oscillators using acceleration sensitivity (Gamma). Analyze sinusoidal and random vibration profiles. Free, instant results.
RL Meas. Error
Calculate return loss measurement uncertainty from coupler directivity and source match. Determine worst-case error bounds for VNA testing. Free, instant results.
Fresnel Zone
Calculate Fresnel zone radius and required clearance for RF line-of-sight links. Determine obstruction margins for microwave and WiFi paths. Free, instant results.
RF Power Density
Calculate power density in W/m² from EIRP and distance using S = EIRP/(4πd²). Get electric field E in V/m, magnetic field H in A/m, and check FCC & ICNIRP EMF safety exposure limits instantly.
Balun Transformer
Calculate balun turns ratio, impedance transformation, and insertion loss for balanced-to-unbalanced feed line matching. Free, instant results.
Link Margin
Calculate RF link margin from TX power, antenna gains, path loss, and receiver sensitivity. Determine max range and fade margin for wireless links. Free, instant results.
Mixer Spurs
Calculate mixer spurious products (m*fLO +/- n*fRF) for receiver design. Identify spurs near the IF passband and optimize LO/IF planning. Free, instant results.
About RF & Microwave Calculators
RF and microwave engineering deals with electromagnetic signals from roughly 300 MHz to 300 GHz — the frequency range where circuit dimensions become comparable to signal wavelengths and lumped-element approximations break down. At these frequencies, transmission line effects dominate: a 50 Ω trace on FR-4 at 5 GHz behaves nothing like a wire, and impedance mismatches cause reflections that waste power and corrupt signals.
The foundational metric is VSWR (voltage standing wave ratio), which quantifies how well a source, transmission line, and load are impedance-matched. A VSWR of 1:1 means perfect match; anything above 2:1 is cause for concern in most RF systems. Return loss, expressed in dB, is the same information in a more convenient form for link budget arithmetic.
Noise figure cascades determine the sensitivity floor of a receive chain. By the Friis formula, the first stage (LNA) dominates: a 1 dB improvement in LNA noise figure is worth more than any gain added later in the chain. Link budgets combine transmit EIRP, free-space path loss, antenna gains, and system noise figure to predict received SNR — the starting point for every wireless system design.
Smith charts visualize complex impedances and enable graphical matching network synthesis. Skin depth calculations matter for conductor loss at microwave frequencies — above a few GHz, current crowds into a thin surface layer, increasing effective resistance. Mastering these tools is the foundation of RF circuit design.