Via Current Capacity Calculator
How much current a plated via carries — annular copper cross-section through the IPC-2221 internal curve, plus via resistance.
Vias in real boards run cooler than the conservative number above because the attached planes act as heatsinks. For high-current paths, use multiple vias in parallel — current capacity scales nearly linearly, and N vias also divide the resistance by N. Thermal vias under a power pad should be filled or capped to avoid solder wicking.
Via Current Calculator computes how much current a plated through-hole via can carry, plus its resistance — free, instant and private in your browser. Layout engineers stitching power nets between layers and reviewing fab plating specs 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 Via Current Capacity Calculator
Via Current Calculator computes how much current a plated through-hole via can carry, plus its resistance using the standard engineering relation: A = π·(d+p)·p for the plating annulus, fed into I = 0.024·ΔT^0.44·A^0.725 (IPC-2221 internal curve). Worked live: a standard 0.3 mm via with 20 µm plating carries about 1 A at a 10 °C rise. 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 Via Current Capacity 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 Via Current Capacity Calculator?
- ✓Implements the real formula — A = π·(d+p)·p for the plating annulus, fed into I = 0.024·ΔT^0.44·A^0.725 (IPC-2221 internal curve) — with the substitution shown, not a black box
- ✓Built for layout engineers stitching power nets between layers and reviewing fab plating specs
- ✓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 via current?+
How much current a plated through-hole via can carry, plus its resistance follows A = π·(d+p)·p for the plating annulus, fed into I = 0.024·ΔT^0.44·A^0.725 (IPC-2221 internal curve). For example, a standard 0.3 mm via with 20 µm plating carries about 1 A at a 10 °C rise. The calculator applies the same relation and shows the substituted arithmetic so you can verify every step.
How many vias do I need for a high-current net?+
Divide the net current by one via's capacity at your allowed rise and add a margin — e.g. a 5 A net with ~1 A vias wants 6. Cluster them tightly so they share current evenly, and prefer several small vias over one large one for reliability.
Does via plating thickness really vary?+
Yes — IPC Class 2 guarantees 20 µm average copper in the barrel, Class 3 requires 25 µm. Budget fabs sit near the minimum, which is exactly what this calculator assumes; specify Class 3 when via current or thermal cycling matters.
Is the Via Current 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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