Safety Design

Clearance & Creepage Calculator

IEC 60664-1 Compliant • Safety Critical Design

Calculate minimum clearance (through air) and creepage (along surface) distances for high-voltage and safety-critical PCB applications.

Safety Parameters

Working Voltage (V peak/DC)

Pollution Degree

Insulation Type

Material Group (CTI)

Operating Altitude (m)

Safety Distances (IEC 60664-1)

Quick Reference: IEC 60664-1 Distances

Voltage	Clearance (PD1)	Clearance (PD2)	Creepage (PD2)
48V	0.04mm	0.4mm	0.6mm
120V	0.15mm	0.5mm	1.2mm
230V	0.35mm	1.5mm	3.2mm
400V	0.60mm	3.0mm	5.0mm
600V	1.00mm	3.0mm	6.3mm

*PD = Pollution Degree. Basic insulation, Material Group II (FR4). Use calculator for precise values.

Understanding Clearance vs Creepage

Clearance (Through Air)

The shortest distance through air between two conductive parts. Prevents electrical breakdown through ionization of air.

•Affected by voltage and pollution degree
•Must account for altitude (reduced air density)
•Direct line-of-sight measurement

Creepage (Along Surface)

The shortest path along the surface of insulating material between conductors. Prevents tracking and surface flashover.

•Affected by material CTI rating
•Must follow actual PCB surface path
•Often larger than clearance requirement

Pollution Degree Selection

PD 1

No Pollution

Sealed enclosure, no pollution. Examples: hermetically sealed equipment, conformal coated PCBs.

PD 2

Non-Conductive

Normal indoor environment. Most common for consumer and industrial electronics. Non-conductive pollution possible.

PD 3

Conductive

Harsh industrial environment. Conductive pollution or dry non-conductive that becomes conductive due to condensation.

Techniques to Increase Creepage

Creepage Slots

Cut slots in the PCB between high and low voltage areas. Each slot adds 2× its depth to the creepage path. Minimum slot width is typically 0.5mm.

Conformal Coating

Apply conformal coating to reduce effective pollution degree. Can allow using PD1 values instead of PD2, significantly reducing required distances.

Ribs and Barriers

Add molded ribs in enclosure design or use insulating barriers on PCB. Each barrier adds 2× its height to the creepage path.

High CTI Materials

Use PCB substrates with higher CTI ratings. High-CTI FR4 (CTI ≥ 600V) requires less creepage than standard FR4 (CTI 400-599V).

Important Safety Notice

This calculator provides guidance based on IEC 60664-1. For safety-critical applications, always consult the full standard and relevant product-specific safety standards (IEC 60950, IEC 62368, etc.). Have designs reviewed by a qualified safety engineer.

Related Safety Tools

Complete your safety-critical PCB design with our other calculators.

Trace Width Calculator Current Capacity Calculator

Clearance & Creepage FAQ

When is creepage larger than clearance?

At higher voltages and lower CTI materials, creepage typically exceeds clearance. Surface tracking is more likely than air breakdown at voltages above ~200V.

What is reinforced insulation?

Reinforced insulation provides protection equivalent to double insulation (two independent insulating layers). It requires 2× the basic clearance and creepage distances.