0.4mm Via Current Calculator
10 Vias | Large Via | IPC-2221 trace formula (approximation)
For 0.4mm (16 mil) via with 25µm plating and 10 via(s):
(2.31A per via)
Via Parameters
MOD: VIA_CUR_V1Capacity Check
10 vias × 2.31 A each
Design Recommendations
Via Sizing Tips
- •Standard via (0.4mm) carries 2.31A per via
- •Cross-sectional area: 33,379 µm²
- •For higher current: use larger vias or increase plating thickness
Via Array Guidelines
- •Parallel vias share current equally when properly connected
- •Place vias in grid pattern near power pins for best distribution
- •Consider thermal vias for heat dissipation from power components
Understanding 0.4mm Via Current Capacity
A 0.4mm (16 mil) plated through hole (PTH) via with standard 25µm copper plating is estimated to carry about 2.31A per via with the IPC-2221 trace-current formula applied to the barrel copper. When using 10 parallel via(s), the total current capacity increases to 23.11A, making this configuration suitable for high-current power applications.
Key Parameters for 0.4mm Via
- Hole Diameter: 0.4mm (16 mil) - large via category
- Plating Thickness: 25µm (standard electroplated copper)
- Board Thickness: 1.6mm (via barrel length)
- Temperature Rise: 10°C (the default used on this page)
- Cross-Section Area: 33,379 µm² per via
- Resistance: 0.843 mΩ per via
Why Use 10 Parallel Via(s)?
Using 10 parallel 0.4mm vias divides the total current load, reducing thermal stress on each individual via and providing redundancy. With 10 vias, the total resistance drops to 0.084 mΩ (compared to 0.843 mΩ for a single via). At the same load current the voltage drop is 10 times lower than with one via; at this page's maximum current (23.11A) the drop is 1.95 mV, the same as a single via at its own limit, because capacity scales with the via count too.
How the Via Current Is Estimated
This page reuses the IPC-2221 trace-current formula I = 0.048 × ΔT^0.44 × A^0.725 (I in A, ΔT in °C, A in mil²), with A taken as the copper ring of the plated barrel. It is an approximation: the formula was fitted to planar traces, not via barrels, so treat the result as a screening estimate and confirm critical designs with your fabricator's plating data and a thermal check. For a 0.4mm hole with 25µm plating the copper ring is 33,379 µm², which gives 2.31A per via at a 10°C rise.
Typical Applications for 0.4mm Via with 23.11A Capacity
Frequently Asked Questions
Can I use fewer than 10 via(s) for 23.11A?
Reducing the number of vias raises the temperature rise above 10°C for the same current, because the same current flows through less copper. Whether a higher rise is acceptable depends on your board's thermal limit; use the calculator above to see the estimate for other via counts.
Should I use filled or hollow vias for 0.4mm?
For large vias like 0.4mm, hollow vias with multiple parallel vias (as shown here with 10 vias) are typically more cost-effective than filled vias. Filled vias provide better thermal performance but at higher manufacturing cost.
What spacing should I use between 10 parallel vias?
The minimum spacing depends on your fabricator's drill-to-drill, annular-ring and pad-size rules, so check their capability sheet. This calculator does not model current sharing between vias; it assumes the vias are identical and carry equal current.
Related Via Current Calculations
0.4 mm × 10 vias compared with other hole sizes
Estimates use 25 µm plating, a 1.6 mm board and 10 °C rise, from the same function as the calculator above.
| Hole | Per via (A) | Vias needed | R per via (mΩ) |
|---|---|---|---|
| 0.2 mm | 1.46 | 16 | 1.59 |
| 0.3 mm | 1.90 | 13 | 1.10 |
| 0.4 mm | 2.31 | 10 | 0.84 |
| 0.5 mm | 2.69 | 9 | 0.68 |
Here 10 parallel vias give a combined resistance of 0.08 mΩ and drop 1.9 mV at the estimated limit. The estimate treats the barrel alone: connecting traces and planes usually limit the real path first. Open the full via calculator. To size the connecting trace, open the trace width calculator prefilled with 23 A (this via set's estimated limit rounded down, not your design current; assumes 1 oz external).
Complete Your PCB Design
After calculating via current for 0.4mm with 10 via(s), use our other free tools to complete your PCB design. Calculate trace widths for power traces, or analyze impedance for high-speed signals.