RF & Microwave Calculators
36 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 online Smith Chart calculator. Plot impedance, calculate VSWR, return loss, and reflection coefficient. No signup — instant results, 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.
Line of Sight
Radio horizon of each antenna, maximum line-of-sight distance between two masts, Earth bulge and first Fresnel-zone radius at any point along the path, and the clearance a link needs there, over a smooth Earth with the k-factor of your choice.
Wilkinson Divider
Design a two-way Wilkinson power divider for any power ratio: the quarter-wave arm impedances, the isolation resistor, the output terminations and their matching transformers, and the physical quarter-wave length, with every line checked against the impedance range your process can make.
Directional Coupler
Design a single-section quarter-wave coupled-line directional coupler: the even- and odd-mode impedances for the coupling you need, the coupled length, the through-path loss and the isolation, with a warning when the coupling is too tight for a single edge-coupled section.
Circular Waveguide
Cutoff frequency of any TE or TM mode of a circular waveguide, the single-mode band between TE₁₁ and TM₀₁, and above cutoff the guide wavelength, phase constant, phase and group velocities, wave impedance and the conductor and dielectric losses; below cutoff, the evanescent attenuation.
Mitered Bend
Optimum mitre for a 90° microstrip bend from the Douville and James relation: the percentage of the corner diagonal to cut away, the cut depth along the diagonal and the chamfer length along each outer edge, ready to draw in a PCB layout.
5G NR Band Lookup
Look up any 5G NR operating band from 3GPP Release 18: uplink and downlink frequencies, duplex spacing, the band's NR-ARFCN range, NR-ARFCN to frequency and back, and the resource blocks for a channel bandwidth and subcarrier spacing.
5G NR Link Budget
A 5G NR link budget on the 3GPP channel models: TR 38.901 path loss for rural macro, urban macro, urban micro and indoor office, LOS or NLOS, the noise floor from the resource blocks, SINR, link margin, the maximum range inside the model's validity and the TS 38.306 peak data rate.
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 and impedance transformation 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.
Reactance Calculator
Calculate inductive reactance (XL = 2πfL) and capacitive reactance (XC = 1/2πfC) for any frequency. Also computes the LC resonant frequency where XL = XC. Essential for filter and impedance matching design.
Doppler Shift
Calculate Doppler frequency shift for radar and RF applications. Computes the Doppler shift (f_d = 2vf·cos θ/c) given transmit frequency, target velocity, and aspect angle. Also derives velocity from measured shift.
Coplanar Waveguide
Calculate coplanar waveguide impedance for CPW and grounded CPW (GCPW/CBCPW). Get Z₀, effective dielectric constant, propagation delay, and the gap width for 50 Ω.
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.
Advanced Simulation Tools
Broadband Impedance Matching Synthesizer
Synthesize L, Pi, T, or ladder matching networks for broadband impedance transformation. Enter source/load impedances across a frequency band and get optimized component values with simulated S-parameters. Export results as Touchstone (.s2p) for ADS/Genesys/scikit-rf.
PDN Impedance Analyzer & Decoupling Capacitor Optimizer
Choose decoupling capacitors for a PCB power delivery network. Enter the plane pair, the regulator and a flat target impedance, and a genetic algorithm finds the capacitor mix that keeps Z_PDN lowest across the decoupling band, which ends at 0.8 × the board's first cavity mode. Above the band the plane-pair cavity sets the impedance; the plot shows its resonances as one observation port sees them, with every capacitor lumped at that port.
FDTD Transmission Line Simulator
Solve microstrip stubs, coupled-line filters, via transitions, and step discontinuities across a ladder of named solve modes — from a 2D cross-section in seconds to a fine 3D openEMS field solve. S-parameters, Smith chart, and impedance analysis.
Satellite & Terrestrial Link Budget
Compute probabilistic link margins using ITU-R propagation models (P.618 rain, P.676 gaseous, P.840 cloud) with climate data read from the ITU-R maps at your site. Enter EIRP, G/T, frequency, and site latitude and longitude. Get a full line-by-line budget, availability curve, and Monte Carlo confidence intervals over rain, pointing, and EIRP/G·T uncertainties.
RF Cascade Budget Analyzer
Compute cascaded noise figure, gain, IIP3, and P1dB for an N-stage RF signal chain using Friis formulas. Paste your stage list as JSON, set your system specs, and get a line-by-line cascade table, sensitivity analysis, and Monte Carlo yield statistics across component tolerances.
Radar Detection Performance Monte Carlo
Compute probability of detection (Pd) vs range for pulsed radar systems. Select Swerling target model (0–IV), specify antenna gains, noise figure, pulse parameters, and rain rate. Monte Carlo over RCS fluctuations and system uncertainties produces Pd confidence bands and ROC curves.
S-Parameter Analysis Pipeline
Upload up to 4 Touchstone files and get component values (L, C, R, Q, self-resonance) for a single component, plus insertion loss, return loss, group delay, TDR and passband ripple — all in one automated report.