Via Current Calculator
PCB Plated Through Hole Current Capacity Analysis
Estimate via current capacity and the number of plated through holes (PTH) for your PCB power delivery design. The calculator applies the IPC-2221 trace power law to the via barrel cross-section as a rough estimate (IPC-2221 itself gives no via formula), so confirm high-current thermal via design with a thermal measurement.
Quick answer
A single 0.3 mm plated via with 25 µm plating in a 1.6 mm board is rated at about 1.9 A at a 10 °C rise by this estimate, so carrying 5 A takes about 3 such vias in parallel.
Worked example (0.3 mm hole, 25 µm plating, 1.6 mm board, 10 °C rise)
| Copper cross-section per via | 0.0255 mm² |
|---|---|
| Current per via | 1.90 A |
| Resistance per via | 1.10 mΩ |
| Vias for 5 A | 3 |
Assumptions
- IPC-2221 provides no via-specific formula; the trace power law (k = 0.048) is applied to the plated barrel cross-section as a rough estimate.
- Equal current sharing between parallel vias is assumed.
Limits
- Plating thickness varies by fabricator and between barrel and surface; confirm with your fabricator.
- The estimate ignores the connecting traces, pads and planes, which usually limit the real path.
Next step
- Size the connecting trace — enter the net current there; the via limit above is not a design current.
- Thermal vs signal vias — heat-spreading vias follow different rules from current-carrying vias.
Via Current Capacity
Calculate the maximum current per via based on hole diameter, plating thickness, and temperature rise. Essential for power delivery network design in high-current PCB applications.
Thermal Via Design
Design thermal vias for heat dissipation from power components. Estimate via current to plan an array for heat transfer to inner copper planes; confirm thermal performance with your fabricator or a thermal analysis.
Via Count Optimization
Determine the minimum number of parallel vias needed for your current requirements. Balance between PCB real estate and thermal/electrical performance.
Via Parameters
MOD: VIA_CUR_V1Capacity Check
1 vias × 1.90 A each
Design Recommendations
Via Sizing Tips
- •Standard via (0.3mm) carries 1.90A per via
- •Cross-sectional area: 25,525 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
Why Via Current Calculation Matters
Prevent Via Failure
Undersized vias can overheat and fail under high current loads. Our calculator gives an estimate to help you size plated through holes for the expected current; apply your own safety margin.
Optimize Power Delivery
Multiple parallel vias reduce total resistance and improve power delivery to your components. Calculate the optimal via count to minimize voltage drop across layer transitions.
Heat Dissipation
Thermal vias conduct heat from surface components to inner copper planes. Proper via sizing and array design is critical for thermal management in power electronics.
How the Via Estimate Works
Our via current calculator applies the IPC-2221 trace power law to the plated barrel cross-section. IPC-2221 provides no via-specific formula, so treat the result as a rough estimate and verify critical designs by measurement.
Via Resistance Analysis
Calculate via resistance and voltage drop for accurate power integrity analysis. Essential for low-voltage, high-current designs where every milliohm matters.
Design Mode
Use our Design Mode to specify your current requirement and automatically calculate the minimum number of vias needed for reliable operation.
Via Current Capacity Technical Guide
Via current capacity is determined by the cross-sectional area of the copper barrel (annular ring) that forms when a plated through hole is drilled and plated. The copper plating on the via barrel wall is typically 18-35µm thick, creating a hollow cylinder of copper that must carry the current between PCB layers.
The current carrying capacity of a via depends on several factors: the finished hole diameter, copper plating thickness, via length (board thickness), and the maximum allowable temperature rise. Using the IPC-2221 formula, we calculate the cross-sectional area of the copper barrel and estimate the via current for your specified parameters (a screening estimate, not a safety rating).
For high-current applications exceeding 1-2A per via, multiple parallel vias are recommended. This approach distributes the current load, reduces total resistance, and improves thermal performance. Our calculator's Design Mode helps you estimate how many vias a given current needs under this formula.
Common Via Sizes
Popular Via Configs
Related Tools
Via current by hole size and via count
Via Current Capacity FAQ
How is via current capacity calculated?
Via current capacity is calculated using the IPC-2221 formula applied to the annular copper ring cross-section. The capacity depends on the via hole diameter, copper plating thickness, and allowable temperature rise. A thicker copper plating (typically 25-35µm) provides more current carrying capacity.
How many vias do I need for high-current applications?
For high-current applications, use multiple parallel vias to share the current load. A common rule is to use enough vias so each carries no more than 0.5-1A to maintain low temperature rise. For 10A, this would mean approximately 10-20 standard vias (0.3mm hole, 25µm plating).
What is the difference between thermal vias and signal vias?
Thermal vias are optimized for heat transfer rather than electrical current. They typically have larger diameters (0.3-0.5mm), filled or capped construction, and are placed in arrays under power components. Signal vias are sized for impedance matching and typically smaller (0.15-0.25mm).
Does plating thickness significantly affect current capacity?
Yes, plating thickness directly affects the copper cross-sectional area. Standard plating (25µm) provides a baseline capacity. Increasing to 35µm (common for power PCBs) increases capacity by approximately 30% (by this site's IPC-2221-based estimate for 0.2–0.5 mm holes at a 10°C rise; the real gain depends on the plating process). Some manufacturers offer 50µm+ for high-current applications.
Should I use filled or hollow vias for power?
For power applications, filled vias (copper or conductive epoxy filled) provide better thermal and electrical performance. However, they cost more. Hollow vias work well when using multiple parallel vias, which is often more cost-effective than fewer filled vias.
How does via length affect current capacity?
Longer vias (thicker PCBs) have higher resistance but the same current capacity at a given temperature rise. The primary concern is via resistance causing voltage drop. For thick boards (>2mm), consider larger via diameters or more parallel vias.
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Need More PCB Design Calculations?
Our via current calculator works alongside our complete suite of PCB design tools. Calculate trace widths for power traces or analyze impedance for high-speed signals. Read our Thermal Via vs Signal Via guide for design best practices.