Verified calculation capability

PCB trace width Calculation Capability

Size PCB copper traces or check ampacity with the IPC-2221 I = k·ΔT^0.44·A^0.725 relation for external and internal layers; optional u_* compose expanded uncertainty on width or I via Uncertainty Engine. · Electrical · Pcb

Capability ID electrical.pcb.trace_width · version 1.1.1

Open calculator REST API MCP Evidence Evidence JSON CVP Manifest Review policy

Model

Current vs area

Current vs area: I = k × ΔT^0.44 × A^0.725
Width from area: w = A / t (t ≈ 1.378 mil × oz)

Solve modes: width · current

Inputs / Outputs

Canonical symbols for this capability. Agent schemas remain the contract.

Symbol	Quantity	Unit	Role
`I`	Trace current (A); required for mode=width	—	input / output
`width_mil`	Trace width (mil); required for mode=current	—	input / output
`dT`	Temperature rise (°C)	—	input / output
`copper_oz`	Copper weight (oz/ft²); default 1	—	input / output
`layer`	k=0.048 external / 0.024 internal	—	input / output
`u_I`	Optional standard uncertainty of I (A); used in mode=width	—	input
`u_width_mil`	Optional standard uncertainty of width_mil (mil); used in mode=current	—	input
`u_dT`	Optional standard uncertainty of dT (°C)	—	input
`u_copper_oz`	Optional standard uncertainty of copper_oz	—	input
`uncertainty_k`	Coverage factor for expanded U on primary result; default 2 when any u_* is set (not the IPC layer k). Requires at least one u_*. Mutually exclusive with confidence.	—	input
`confidence`	Optional coverage probability instead of uncertainty_k. Requires at least one u_*.	—	input
`width`	—	mm	output
`area_mil2`	—	—	output
`thickness_mil`	—	—	output
`k`	—	—	output
`uncertainty`	Present when any u_* is provided; composed via engineering.uncertainty.propagate on width_mil (mode=width) or I (mode=current)	—	output

Assumptions / Validity

Declared scope for this capability. Do not use it outside this domain.

Assumptions

Classic IPC-2221 closed form; not IPC-2152 charts.
1 oz/ft² ≡ 1.378 mil thickness.
Steady current; no via heating or nearby power planes.
When u_* are set, first-order GUM sensitivity with independent inputs (no ρ on this page).

Example

One numerical check. The calculator page holds worked steps and FAQ.

I=10 A, ΔT=10 °C, 1 oz external → width ≈ 283.2 mil

Open this example in the calculator

Trust

CVP VERIFIED · CVP protocol 1.0.0-proposed · Engineering assurance. Computational verification is defined by CVP. Supplemental domain review (internal) and named expert review are defined by the Review policy and do not by themselves determine CVP conformance.

CVP: CVP VERIFIED · CVP protocol 1.0.0-proposed · Engineering assurance· View Manifest · CVP overview · Specification
Assurance: Engineering
Declared partition coverage: PASS · 4/4 declared partitions (width-external, width-internal, current, invalid-domain)
Calculation version: 1.1.1
Verification: 15/15 calculation tests · 3/3 legacy golden · 6/6 legacy boundary · 6/6 legacy property
Production surface contract: 6/6
Versions: Calculation 1.1.1 · CVP protocol 1.0.0-proposed · Evidence 2026-09-11.schema-coverage-u
Verification revision: 2026-09-11.schema-coverage-u · 6/6 property · digest 5252bebde7a8
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.
CVP suite: 3/3 golden · 5/5 CVP boundary · 4/4 invalid · 6/6 property · 1/1 cross-interface · 6/6 CVP contract
Supplemental domain review: Internal · Pass · electrical-engineer
Named expert review: Not performed
Version lock: Supported (409 VERSION_MISMATCH)
Artifact consistency: Build verified · 1.1.1 (workspace artifacts agree)
Review-policy tier: Internal engineering review — catalog token expert_verified; supplemental; not CVP status

This calculator CURRENT · Public schema 1.1.1 matches · Semantic contract ✓ · Production attested · Public/cache ✓ · Origin ✓

Call this capability

Human page, REST, and MCP share the same engine and calculation_version. Build verified hashes workspace artifacts only. After deploy, attest:production GETs canonical URLs twice — the public/cached view an Agent actually hits, and origin — including every /capabilities/{id} HTML page. Public Capability HTML version must match catalog before production attestation passes. Live Trust rows above fetch /.well-known/calculatorx-production-attestation.json and the output schema const. Build hashes: release integrity. That proves currently published page / engine / schema / evidence / MCP agree — not that a historical version is independently immutable. Reference Calculation Standard — Production surface contract 6/6.

Tool id: pcb-trace-width
Engine: pcb-trace-width
REST: POST /api/v1/calc/pcb-trace-width
MCP: execute_calculation with capability_id: "electrical.pcb.trace_width"
Agent input schema: Canonical (MCP / Agent)
Output schema: JSON Schema (latest)
Versioned input schema: Immutable pin (1.1.1)
Versioned output schema: Immutable pin (1.1.1)

Operations

Declared calculation modes for this capability.

width
current

References

Human-readable sources plus CVP reference evidence classes.

Sources

IPC-2221 — Generic Standard on Printed Board Design — Conductor width and current capacity (external/internal k factors)
IPC-2152 — Standard for Determining Current-Carrying Capacity in Printed Board Design — Updated current-carrying methodology

Reference evidence classes: O1 model · O2 expected_values · O2 numerical_behavior

Try with an agent

Inspect this capability via same-origin MCP, then call execute_calculation.

curl -sS -X POST 'https://www.calculatorx.com/mcp' \
  -H 'Content-Type: application/json' \
  -H 'MCP-Protocol-Version: 2026-07-28' \
  -H 'Mcp-Method: tools/call' \
  -H 'Mcp-Name: inspect_capability' \
  -d '{"jsonrpc":"2.0","id":1,"method":"tools/call","params":{"name":"inspect_capability","arguments":{"capability_id":"electrical.pcb.trace_width"}}}'

Inspect the trust tier and required assurance level before execution. Pin calculation_version (1.1.1) when reproducibility matters. Full protocol notes: MCP docs.