Electrical calculator

Via Current Capacity Calculator

Estimate PCB via ampacity from drill diameter, plating thickness, and temperature rise using the IPC-2221 I = k·ΔT^0.44·A^0.725 relation on the plating cross-section.

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Instant result

Result

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Enter values to calculate.

Inputs—

Mode—

Formula—

Trust summary CVP VERIFIED · CVP protocol 1.0.0-proposed · Engineering assurance

Input interpretation: Enter values to calculate.
Result: —
Assurance: Engineering
Declared partition coverage: PASS · 3/3 declared partitions (current, drill, invalid-domain) · Matrix
Known limitations: SI metres for drill/plating; ampacity via mil²
Core CVP does not include live graph, viewport, or pointer interaction.
Model: Via ampacity or required drill from IPC-2221 plating cross-section.
Scope: IPC-2221 closed form; external k; uniform plating
Verification: Engine tested · Source checked · v1.0.0 · CVP VERIFIED · CVP protocol 1.0.0-proposed · Engineering assurance· View Manifest · CVP overview · Specification
Versions: Calculation 1.0.0 · CVP protocol 1.0.0-proposed
CVP identity: 3/3 property · digest 345917295ac4
Legacy regression: 7/7 tests · Production surface contract 4/4
Reference: O1 model · O2 expected_values · O2 numerical_behavior
Interfaces: PASS · UI (SSR) / REST / MCP — ui-ssr is query-result HTML, not a live browser session.
Supplemental domain review: Internal · Pass · electrical-engineer
Named expert review: Not performed
CVP suite: 2/2 golden · 2/2 CVP boundary · 2/2 invalid · 3/3 property · 1/1 cross-interface · 1/1 CVP contract · Manifest
Sources: IPC-2221 — Generic Standard on Printed Board Design — Conductor current capacity
IPC-2152 — Standard for Determining Current-Carrying Capacity — Via / conductor thermal ampacity guidance
Sources
Evidence: 2 legacy golden · 2 legacy boundary · legacy regression suite · 2/2 oracle-backed golden · 2/2 invalid · Artifact integrity PASS · CalculatorX electrical review
Semantic contract: PASS

Full verification

Manifest identity, reference classes, interfaces, suite, and production records.

Formulas

Core equations used by this calculator.

Plating areaA = π · t · (d − t)

CurrentI = k · ΔT^0.44 · A^0.725

iSame closed form as Trace Width external k. Not a thermal CFD; IPC-2152 may differ.

How to use

Enter drill diameter and plating thickness

Both must be greater than zero for via copper cross-section.

Enter allowed temperature rise ΔT

ΔT > 0 sets the IPC-style current capacity estimate used by the tool.

Read via current capacity

Result is an approximate continuous current for the given rise—not a full thermal FEM.

Example calculations

Common configurations with formula and result.

0.3 mm drill · 25 µm plate · 10 °C

Single via

mode=current

I ≈ 1.69 A

Via Current Capacity calculator specification

Version 1.0.0 · Engine tested · Supplemental domain review · Internal · 2026-08-08

Calculation status

Engine tested 7/7 tests · Production surface contract 4/4
Supplemental domain review Internal · Pass · electrical-engineer · 2026-08-08
Named expert review Not performed
Calculation version 1.0.0

Review policy · Evidence · Reviewed by CalculatorX electrical review (electrical-engineer)

Definition: Via ampacity is estimated from the annular plating cross-section A = π·t·(d − t) with the IPC-2221 current relation I = k·ΔT^0.44·A^0.725 (k=0.048, A in mil²).
What it calculates: Via ampacity or required drill from IPC-2221 plating cross-section.
Inputs: mode: current | drill
dT > 0; t_plating_m > 0 (default 25e-6); n_vias ≥ 1
d_drill_m (current) or I_A (drill)
Outputs: I_A
I_one_A
d_drill_m
A_mil2
…
Formula: A=πt(d−t); I=k·ΔT^0.44·A^0.725; k=0.048
Assumptions: IPC-2221 closed form; external k; uniform plating
Units: m, °C, A
Boundary conditions: t ≥ d/2 → PLATING_TOO_THICK
Bad n_vias → N_VIAS_MUST_BE_POSITIVE_INT
Example: d=0.3 mm, t=25 µm, ΔT=10 °C → I≈1.69 A
Validation cases: 2 published on this page · 7/7 tests · Production surface contract 4/4 · View evidence
d=0.3mm, t=25µm, dT=10 → I≈1.685
I=1 A → solve drill → d≈0.159 mm
Sources: IPC-2221 — Generic Standard on Printed Board Design — Conductor current capacity
Supports: I = k·ΔT^0.44·A^0.725 applied to via plating area
IPC-2152 — Standard for Determining Current-Carrying Capacity — Via / conductor thermal ampacity guidance
Supports: Temperature-rise ampacity context for plated vias
Last reviewed: 2026-08-08
Reviewed by: CalculatorX electrical review (electrical-engineer)
Calculation version: 1.0.0

Background

Interpretation and common distinctions.

Estimate via current capacity from drill, plating, and ΔT (IPC-2221 plating area).

Default: 0.3 mm drill · 25 µm plate · 10 °C → ≈ 1.69 A.

Agent / API notes

Capability id: electrical.pcb.via_current · tool id: pcb-via-current · pin 1.0.0.

Other calculators in this family: Microstrip Impedance Calculator, PCB Differential Impedance Calculator, PCB Trace Thermal Calculator, PCB Trace Width Calculator (IPC-2221), Stripline Impedance Calculator . Explore all PCB & Signal Integrity.

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Frequently asked questions

Key distinctions behind the calculation.

Why plating thickness matters?

Current flows in the barrel plating. Area ≈ π·t·(d−t); thicker plating or larger drill carries more current.

What if plating ≥ drill/2?

The API returns PLATING_TOO_THICK.