Creepage/Clearance Estimate

clearance ≈ Vpeak / 500 mm

Quick answer

This calculator solves clearance_mm ≈ V_peak / 500 for clearance ≈ Vpeak / 500 mm. With Peak Working Voltage 12 V, the result is 0.024.

Calculator

Result
—

Formula

clearance_mm ≈ V_peak / 500

Description

Creepage and clearance are the minimum distances required between conductors at different potentials to prevent electrical breakdown. Clearance is the shortest distance through air; creepage is the shortest distance along the surface of insulation. This rough estimate (Vpeak/500 mm) provides a starting point for PCB layout, but actual requirements depend on the safety standard (IEC 62368, IEC 60950, UL), pollution degree, altitude, insulation type (basic, supplementary, reinforced), and material group. Always consult the applicable safety standard for the final design.

Variables

  • V_peak — Peak working voltage between conductors (V)

Practical Notes

The result is in millimeters (using the forward solver). For 230 V mains (325 Vpeak), the estimate is about 0.65 mm clearance, but IEC 62368-1 typically requires 1.5-2.5 mm depending on conditions. At higher altitudes (above 2000 m), clearance must be increased due to lower air pressure. Creepage depends on the Comparative Tracking Index (CTI) of the PCB material. Standard FR-4 is CTI group IIIb (175-249 V). Slots and grooves in the PCB can increase the effective creepage distance.

Symbols and units

Symbol Meaning Default unit Accepted units
Vpeak Peak Working Voltage V pV, nV, µV, mV, V, kV

Step by step

  1. 1. What you know: Peak Working Voltage 12 V
  2. 2. The relation: clearance_mm ≈ V_peak / 500
  3. 3. Substitute: Vpeak = 12 V
  4. 4. Result: clearance ≈ Vpeak / 500 mm = 0.024

Worked examples

Minimum range

Given: Peak Working Voltage 0.33 V

Result: clearance ≈ Vpeak / 500 mm = 6.6 × 10⁻⁴

Low range

Given: Peak Working Voltage 3.3 V

Result: clearance ≈ Vpeak / 500 mm = 0.0066

Typical

Given: Peak Working Voltage 12 V

Result: clearance ≈ Vpeak / 500 mm = 0.024

High range

Given: Peak Working Voltage 0.23 kV

Result: clearance ≈ Vpeak / 500 mm = 0.46

Maximum range

Given: Peak Working Voltage 2.3 kV

Result: clearance ≈ Vpeak / 500 mm = 4.6

How clearance ≈ Vpeak / 500 mm changes with Peak Working Voltage

Peak Working Voltage (input) clearance ≈ Vpeak / 500 mm (result)
1.2 V 0.0024
3 V 0.006
6 V 0.012
9 V 0.018
12 V 0.024
18 V 0.036
24 V 0.048
48 V 0.096
84 V 0.168
120 V 0.24

Embed this calculator

Paste this into any page. It keeps working when this page updates, and credits the source.

<iframe src="https://vbatpower.com/embed/creepage-clearance/" width="100%" height="460" style="border:1px solid #1f2a37;border-radius:12px" loading="lazy" title="Creepage/Clearance Estimate"></iframe>
<p><a href="https://vbatpower.com/formulas/creepage-clearance/">Creepage/Clearance Estimate</a> Calculator by vbatpower.com</p>

Frequently asked questions

How do you calculate Creepage/Clearance Estimate?

Use clearance_mm ≈ V_peak / 500. With Peak Working Voltage 12 V, clearance ≈ Vpeak / 500 mm works out to 0.024.

What is the formula for Creepage/Clearance Estimate?

The formula is clearance_mm ≈ V_peak / 500. Creepage and clearance are the minimum distances required between conductors at different potentials to prevent electrical breakdown.

Related Concepts

All PCB & Traces formulas →
Trace Current Capacity (IPC-2221) Trace Resistance Trace Voltage Drop Via Current Capacity (IPC-2221) Microstrip Impedance Stripline Impedance Differential Pair Impedance Creepage/Clearance Estimate

Need more features?

Save calculations, import telemetry data, simulate battery discharge, and collaborate with your team.

Try the App