0.4mm Via Current Calculator
3 Vias | Large Via | IPC-2221 trace formula (approximation)
For 0.4mm (16 mil) via with 25µm plating and 3 via(s):
(2.31A per via)
Via Parameters
MOD: VIA_CUR_V1Capacity Check
3 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 3 parallel via(s), the total current capacity increases to 6.93A, 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 3 Parallel Via(s)?
Using 3 parallel 0.4mm vias divides the total current load, reducing thermal stress on each individual via and providing redundancy. With 3 vias, the total resistance drops to 0.281 mΩ (compared to 0.843 mΩ for a single via). At the same load current the voltage drop is 3 times lower than with one via; at this page's maximum current (6.93A) 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 6.93A Capacity
Frequently Asked Questions
Can I use fewer than 3 via(s) for 6.93A?
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 3 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 3 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 × 3 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 | 5 | 1.59 |
| 0.3 mm | 1.90 | 4 | 1.10 |
| 0.4 mm | 2.31 | 3 | 0.84 |
| 0.5 mm | 2.69 | 3 | 0.68 |
Here 3 parallel vias give a combined resistance of 0.28 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 6.5 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 3 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.