HomeCalculatorsElectricalPCB & Signal IntegrityStripline Impedance Calculator
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Stripline Impedance Calculator

Estimate symmetric stripline characteristic impedance from W, b, and εr. Extends microstrip / Zdiff. Runs locally in your browser.

Instant result
Result
—

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 · 2/2 declared partitions (stripline, invalid-domain) · Matrix
Known limitations
  • Zero thickness; er≥1
  • Core CVP does not include live graph, viewport, or pointer interaction.
Model
Symmetric stripline Z0.
Scope
Zero thickness; symmetric; no soldermask
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
2/2 property · digest 96121e35234e
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
1/1 golden · 3/3 CVP boundary · 2/2 invalid · 2/2 property · 1/1 cross-interface · 1/1 CVP contract · Manifest
Sources
  • IPC-2141A / Wadell — Symmetric stripline
  • Pozar / microwave engineering texts — Stripline characteristic impedance
Sources
Evidence
2 legacy golden · 3 legacy boundary · legacy regression suite · 1/1 oracle-backed golden · 2/2 invalid · Artifact integrity PASS · CalculatorX electrical review
This calculator CURRENT · Public schema 1.0.0 matches · Semantic contract ✓ · Production attested · Public/cache ✓ · Origin ✓
Semantic contract
PASS
Full verification

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

Formulas

Core equations used by this calculator.

Narrow (W/b < 0.35)Z0 = (60/√εr)·ln(4b/(πW))
Wide (W/b ≥ 0.35)Z0 = 30π / (√εr·(W/b+0.441))
iApproximate; ignores thickness and soldermask. Use a field solver for fabrication.

How to use

1

Enter strip width W and ground-plane spacing b

Both must be greater than zero (meters).

2

Enter dielectric constant εr

εr ≥ 1 for the stripline medium.

3

Read characteristic impedance Z0

Z0 = (60/√εr)·ln(4b/(πW)) (symmetric stripline approx).

Example calculations

Common configurations with formula and result.

ϟ

FR4 sample

W=0.2 mm · b=0.4 mm · εr=4.2

wide branch
Z0 ≈ 49 Ω

Stripline Impedance calculator specification

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

Calculation status

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

Definition
A symmetric stripline is a trace centered between two ground planes. Z0 depends on width W, plane spacing b, and dielectric εr. Piecewise approximations are used for narrow and wide strips.
What it calculates
Symmetric stripline Z0.
Inputs
  • W_m>0
  • b_m>0
  • er≥1
Outputs
  • Z0_ohm
  • W_over_b
Formula
Piecewise IPC-style stripline
Assumptions
  • Zero thickness; symmetric; no soldermask
Units
  • m → Ω
Boundary conditions
  • W,b≤0 → VALUE_MUST_BE_POSITIVE
Example
W=2e-4 b=4e-4 er=4.2 → ≈49 Ω
Validation cases

1 published on this page · 7/7 tests · Production surface contract 4/4 · View evidence

  • W=2e-4 b=4e-4 er=4.2 → Z0≈48.9
Sources
  • IPC-2141A / Wadell — Symmetric stripline
    Supports: Piecewise Z0 approximations
  • Pozar / microwave engineering texts — Stripline characteristic impedance
    Supports: Piecewise narrow/wide Z0 approximations
Last reviewed
2026-08-08
Reviewed by
CalculatorX electrical review (electrical-engineer)
Calculation version
1.0.0

Background

Interpretation and common distinctions.

Estimate stripline Z0.

Supported and not supported

Supported — Symmetric stripline · API electrical.pcb.stripline

Not supported — Asymmetric stripline, thickness correction

Agent / API notes

Capability id: electrical.pcb.stripline · tool id: pcb-stripline · 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), Via Current Capacity Calculator . Explore all PCB & Signal Integrity.

→ Microstrip Impedance Calculator Compute microstrip characteristic impedance Z0 from W/H/εr, or synthesize width for a target Z0 (zero-thickness IPC-2141 / Wadell–Hammerstad). Runs locally in your browser. › → PCB Differential Impedance Calculator Estimate edge-coupled microstrip differential impedance Zdiff from W, H, S, and εr. Hammerstad/Wadell Z0 plus IPC-2141A-style coupling. Runs locally in your browser. › → PCB Trace Thermal Calculator Estimate copper trace I²R power and temperature rise with a board thermal resistance. Runs locally in your browser. › → PCB Trace Width Calculator (IPC-2221) Size PCB copper traces from current and temperature rise using the classic IPC-2221 I = k·ΔT^0.44·A^0.725 relation for external and internal layers. Runs locally in your browser. › → 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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Frequently asked questions

Key distinctions behind the calculation.

Microstrip or stripline?

Microstrip has one reference plane (outer layer). Stripline is embedded between two planes.