PCB Via Current & Size Calculator
Calculate maximum current capacity for PCB vias based on IPC-2152 standards, and get the smallest via size for a given current. The via size calculator runs the same formula in both directions.
PCB Via Current & Size Calculator
Estimate how much current a plated via can safely carry, compare parallel via capacity, and review via resistance before final fabrication review.
Finished hole diameter (0.2mm - 1.0mm typical)
Standard: 25μm, Heavy copper: 50μm+
Via Cross-Section
D = Diameter, T = Plating Thickness
When to use this calculator
Use it when current has to move between layers and you need to estimate whether one via or a via array can safely carry the expected load.
Check how many vias you may need in parallel when routing high-current paths through thick boards or compact layouts.
Use the estimate as an engineering review input when discussing plating thickness, finished hole size, and reliability with your fabricator.
Key Features
IPC-Based Calculation
The via size calculator uses proven IPC-2152/2221 formulas for accurate current capacity estimation based on thermal constraints.
Parallel Via Support
Calculate total current capacity for multiple vias in parallel, essential for high-current power designs.
Resistance Calculation
Also calculates via resistance to help you estimate voltage drop and power dissipation.
Related resources & next steps
Estimate current capacity for the connected traces after validating how current moves through vias.
Check whether the trace connected to the via array is also wide enough for the expected load.
Review via plating, aspect ratio, and fabrication constraints with manufacturing support.
Send your via structure, current requirement, and stackup details for engineering review.
Frequently Asked Questions
What is the standard via plating thickness?
Standard via plating thickness is typically 25μm (1 mil). For high-current applications, manufacturers can plate up to 50μm or more. The IPC-A-600 Class 2 standard requires a minimum of 20μm average plating thickness.
How many vias do I need for high-current traces?
Use this calculator to determine current per via, then divide your required current by this value. Always add a safety margin of 20-50%. For example, if each via can carry 1A and you need 5A, use at least 6-8 vias.
What temperature rise should I use?
A 10°C rise is conservative and commonly used. For designs with good thermal management or short duty cycles, 20°C may be acceptable. Never exceed 45°C rise as this approaches solder reflow temperatures.
Are blind and buried vias different?
The calculation method is the same, but via length differs. For blind vias, use the actual via depth instead of full board thickness. Buried vias should use the distance between connected layers.
What is the smallest via that can carry 1 A?
A 0.2 mm finished hole with 25 µm plating carries about 1.4 A at a 10 °C rise, so a single via covers 1 A with a small margin. The via size calculator table above lists the current capacity of every standard size.
How do I calculate the via pad diameter?
Pad diameter is the finished hole plus twice the annular ring. Most fabricators specify a 0.05 mm (2 mil) minimum ring; 0.10 to 0.15 mm is common where drill registration is less certain. Enter the ring in the via size calculator above and it returns the matching pad diameter.
Need help validating via current capacity in a real production stackup?
If your design depends on heavy current transfer, stacked vias, or challenging thermal conditions, we can review manufacturability, plating assumptions, and reliability before fabrication.
Via Size Calculator: Size a Via from the Current
Enter the current a via must carry and get the smallest finished hole, drill and pad that will hold it safely. This is the same via size calculator, solved for diameter instead of current.
Current per via, at the temperature rise set below
0.05 mm (2 mil) minimum; 0.10 mm or more preferred
Standard via sizes at 25 µm plating and 10 °C rise
| Finished hole | Pad diameter | Current capacity | Aspect ratio (1.6 mm) |
|---|---|---|---|
| 0.20 mm | 0.50 mm | 1.5 A | 8.0:1 |
| 0.25 mm | 0.55 mm | 1.7 A | 6.4:1 |
| 0.30 mm | 0.60 mm | 1.9 A | 5.3:1 |
| 0.40 mm | 0.70 mm | 2.3 A | 4.0:1 |
| 0.50 mm | 0.80 mm | 2.7 A | 3.2:1 |
| 0.60 mm | 0.90 mm | 3.1 A | 2.7:1 |
How the via size calculator picks a size
- Via size follows from three things: the current it must carry, the plating thickness your fabricator can hold, and the annular ring your design rules allow. Change any one of them in the via size calculator and the other two move with it.
- A 0.3 mm via with 25 µm plating carries about 1.9 A at a 10 °C rise. Current scales with copper cross-section, so doubling the plating thickness or the hole diameter adds roughly 70 % more capacity.
- Below 0.2 mm finished hole, plating uniformity drops and cost rises. Use smaller vias only where routing requires it, and confirm the aspect ratio with the fabricator.
How to Use This Calculator
- 1
Enter Via Diameter
Input the finished hole diameter of your via in millimeters.
- 2
Set Plating Thickness
Enter the copper plating thickness (typically 18-50μm).
- 3
Configure Parameters
Set number of vias, board thickness, and acceptable temperature rise.
- 4
Get Results
Click calculate to see max current per via and total capacity, or switch to the via size calculator below to size a via from a target current.
Worked Examples
These three runs come straight out of the via size calculator above. Use them to sanity-check your own drill chart before you release it.
| Input | Calculated via | What it tells you |
|---|---|---|
| 1 A · 10 °C · 1.6 mm · 25 μm | 0.15 mm / 0.45 mm · 10.7:1 | At 1 A the current is not the limit: the formula asks for a 0.11 mm hole, so the 0.15 mm fabrication floor sets the via size and the annular ring sets the pad. |
| 2 A · 20 °C · 1.6 mm · 25 μm | 0.25 mm / 0.55 mm · 6.4:1 | Doubling the allowed temperature rise from 10 °C to 20 °C halves the copper needed, so 2 A fits a 0.25 mm hole that still drills at 6.4:1. |
| 5 A · 30 °C · 2.4 mm · 30 μm | 0.50 mm / 1.00 mm · 4.8:1 | A 5 A power via on a 2.4 mm backplane needs a 0.50 mm finished hole; the 0.25 mm annular ring then pushes the pad to 1.00 mm. |