PCB Trace Inductance Calculator
Self-inductance of a straight trace (Grover formula) with nH/mm and reactance at 100 MHz — why long decoupling traces ruin bypassing.
This is the free/partial inductance — a trace routed tightly over a ground plane forms a loop with much lower effective inductance, and the loop area is what matters for decoupling and EMI. Use this number for ground-lead spikes, current-shunt layouts and why a 10 mm decoupling-cap trace (~10 nH) ruins high-frequency bypassing.
Trace Inductance Calculator computes the self-inductance of a straight PCB trace and its reactance at frequency — free, instant and private in your browser. Anyone fighting decoupling problems, ground bounce or current-shunt ringing 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 PCB Trace Inductance Calculator
Trace Inductance Calculator computes the self-inductance of a straight PCB trace and its reactance at frequency using the standard engineering relation: L(µH) = 0.00508·l·[ln(2l/(w+t)) + 0.5 + 0.2235(w+t)/l] (Grover, dimensions in inches). Worked live: a 25 mm × 0.3 mm trace is about 23 nH — already 14 Ω of reactance at 100 MHz. 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 PCB Trace Inductance 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 PCB Trace Inductance Calculator?
- ✓Implements the real formula — L(µH) = 0.00508·l·[ln(2l/(w+t)) + 0.5 + 0.2235(w+t)/l] (Grover, dimensions in inches) — with the substitution shown, not a black box
- ✓Built for anyone fighting decoupling problems, ground bounce or current-shunt ringing
- ✓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 trace inductance?+
The self-inductance of a straight PCB trace and its reactance at frequency follows L(µH) = 0.00508·l·[ln(2l/(w+t)) + 0.5 + 0.2235(w+t)/l] (Grover, dimensions in inches). For example, a 25 mm × 0.3 mm trace is about 23 nH — already 14 Ω of reactance at 100 MHz. The calculator applies the same relation and shows the substituted arithmetic so you can verify every step.
Why must decoupling capacitors sit close to the IC?+
Every millimetre of trace adds roughly 1 nH, and at 100 MHz each nanohenry is ~0.6 Ω. A capacitor 10 mm away fights ~6 Ω of inductive reactance — useless for fast transients. Short fat traces and via-to-plane placement keep the loop small.
Does a ground plane change the trace's inductance?+
Dramatically. This tool gives the partial (free) inductance; a trace routed tightly over its return plane forms a small loop whose effective inductance is far lower. That is the entire argument for unbroken ground planes under fast signals.
Is the Trace Inductance 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.
Related Electronics tools
PCB Trace Width Calculator (IPC-2221)
Minimum trace width for your current and temperature rise — IPC-2221 formula with copper weight, layer choice and a step-by-step worked example.
● LiveMicrostrip Impedance Calculator
Z₀ of a surface microstrip from width, height and εr (IPC-2141A), plus effective dielectric constant and propagation delay.
● LiveStripline Impedance Calculator
Characteristic impedance of an embedded stripline trace from geometry and εr — the inner-layer companion to the microstrip tool.
● Live