rftools.io — Free RF & Electronics Calculators, Simulation Tools & Reference

# rftools.io > Free, accurate RF & electronics calculators for engineers. 213 interactive calculators covering 13 categories, plus 13 advanced simulation tools. ## API - Base URL: https://rftools.io/api/py/v1 - POST /calculate — Run a calculator: `{"slug": "microstrip-impedance", "inputs": {"traceWidth": 1.0, "substrateHeight": 1.6, "dielectricConstant": 4.4, "copperThickness": 35}}` - Docs: https://rftools.io/docs/api ## MCP Server Install via npm (no setup required): ```json { "mcpServers": { "rftools": { "command": "npx", "args": ["-y", "rftools-mcp"], "env": { "RFTOOLS_API_KEY": "rfc_your_key_here" } } } } ``` Omit `env` for calculators-only (no API key needed). Get a key at https://rftools.io/dashboard Calculator tools (no key): `list_calculators`, `get_calculator_info`, `run_calculation` Simulation tools (API key): `list_simulation_tools`, `run_simulation` ## Calculator Categories - **RF & Microwave** (28 calculators): microstrip impedance, VSWR/return loss, link budget, Smith chart, coax impedance, coax loss, noise figure cascade, skin depth, waveguide cutoff, radar range, free-space path loss, Fresnel zone, power density, balun transformer, link margin, mixer spur, ISM coexistence, reactance (XL/XC), Doppler shift, and more - **PCB Design** (13 calculators): trace width/current, controlled impedance, differential pair, via calculator, stackup builder, crosstalk, decoupling, trace inductance, power plane impedance, via stub resonance, solder paste volume, and more - **Power Electronics** (21 calculators): voltage divider, buck/boost/flyback converter, LDO thermal, battery life, PWM duty cycle, MOSFET power dissipation, solar panel sizing, transformer turns ratio, supercapacitor backup, cable voltage drop (NEC), and more - **Signal Processing** (13 calculators): filter designer, ADC SNR, FFT bin resolution, Johnson noise, PLL loop filter, BER vs SNR, sampling/Nyquist, quantization noise, and more - **Antenna Design** (8