L-Network Impedance Matching Calculator
Series-L / shunt-C values to match any two resistances at your frequency — with network Q and bandwidth shown.
Shown is the LOW-PASS version (series L, shunt C) — it also filters harmonics, which is why PAs use it. Swap L↔C for the high-pass twin (blocks DC instead). The Q is FIXED by the resistance ratio — if you need narrower or wider bandwidth, cascade two L-sections (π or T network) and pick an intermediate resistance.
L-Network Matching Calculator computes the two-component L-network that matches one resistance to another — free, instant and private in your browser. RF builders matching PAs, RFID coils and antennas without a tuner use it to skip the datasheet algebra: type your numbers, read the answer with the substituted formula shown step by step, and share an exact permalink of the calculation.
About L-Network Impedance Matching Calculator
L-Network Matching Calculator computes the two-component L-network that matches one resistance to another using the standard engineering relation: Q = √(R(high)/R(low) − 1); X(series) = Q·R(low); X(shunt) = R(high)/Q; then L = X/2πf, C = 1/2πfX. Worked live: matching 50 Ω to a 12 Ω load at 13.56 MHz takes a 250 nH series inductor and a 660 pF shunt capacitor. The result recalculates on every keystroke, the worked-example panel shows your numbers substituted into the formula, and the Copy permalink button encodes the inputs in the URL so a colleague opens exactly your calculation. Everything runs client-side — nothing you type leaves your device.
How to use L-Network Impedance Matching Calculator
- 1Enter your values — the tool starts with realistic defaults for this exact use case, so the worked example is meaningful immediately.
- 2Read the live result and the worked-example panel, which substitutes your numbers into the formula step by step.
- 3Adjust any input to compare scenarios, then use Copy result or Copy permalink to share the calculation.
Why use L-Network Impedance Matching Calculator?
- ✓Implements the real formula — Q = √(R(high)/R(low) − 1) — with the substitution shown, not a black box
- ✓Built for RF builders matching PAs, RFID coils and antennas without a tuner
- ✓Copy result and permalink buttons — share the exact calculation in a README, forum answer or design review
- ✓100% free, no sign-up, runs entirely in your browser (works offline once loaded)
Frequently asked questions
How do you calculate l-network matching?+
The two-component L-network that matches one resistance to another follows Q = √(R(high)/R(low) − 1); X(series) = Q·R(low); X(shunt) = R(high)/Q; then L = X/2πf, C = 1/2πfX. For example, matching 50 Ω to a 12 Ω load at 13.56 MHz takes a 250 nH series inductor and a 660 pF shunt capacitor. The calculator applies the same relation and shows the substituted arithmetic so you can verify every step.
Which way around do the L-network components go?+
The shunt element always goes across the HIGHER resistance side, the series element connects to the lower. Low-pass version (series L, shunt C) also suppresses harmonics — the default for transmitter outputs; swap L↔C for a high-pass that blocks DC.
My load isn't purely resistive — can I still use this?+
Yes: first absorb the load's reactance (cancel it with the series element or fold it into the calculation), then match the remaining resistance. Antenna analyzers report R + jX precisely so you can do this — or retune the antenna to resonance first, leaving only R.
Is the L-Network Matching Calculator free and private?+
Yes — completely free with no sign-up or usage limits, and it runs entirely in your browser: the values you enter are never uploaded or stored on a server.
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