Clearance & Creepage Checklist
Record the insulation questions that a Circuit Edge layout brief must resolve before numerical spacing can be approved.
Design inputs
01 / CONFIGURECalculation workspace
02 / EXPLOREThis is guidance, not an IEC table lookup or compliance calculator. No numerical safe spacing is generated. Confirm against the applicable edition of IEC 60664-1 and the relevant product standard. Results are estimates; confirm critical designs with your fabricator.
How it works · formula & assumptions
Clearance is the shortest distance through air. Creepage is the shortest distance along an insulating surface. No universal voltage-only formula establishes either requirement.
This is guidance, not an IEC table lookup or compliance calculator. No numerical safe spacing is generated. Confirm against the applicable edition of IEC 60664-1 and the relevant product standard.
Which circuits need separation, and why?
Which circuits need separation, and why?
For a board with mains, a high-voltage bus or an isolated interface, identify the two sides of the barrier and the insulation function before choosing a distance. A voltage field alone cannot describe that requirement.
Keep the insulation evidence attached to the layout
The Circuit Edge review note should record the applicable product standard, edition, working-voltage definition, impulse conditions, environment and material evidence. Have a qualified reviewer approve the barrier. The checklist records missing decisions and never declares a safe spacing from incomplete information.
The question this Circuit Edge workspace addresses
Record the insulation questions that a Circuit Edge layout brief must resolve before numerical spacing can be approved. This is guidance, not an IEC table lookup or compliance calculator. No numerical safe spacing is generated. Confirm against the applicable edition of IEC 60664-1 and the relevant product standard.
Formula and assumptions
Clearance is the shortest distance through air. Creepage is the shortest distance along an insulating surface. No universal voltage-only formula establishes either requirement.
Start with insulation coordination
Clearance is an air path and creepage is a surface path. They respond to different stresses and cannot be reduced to the same voltage-to-distance multiplier. A working voltage entry is only one part of the problem. Establish whether it is RMS, DC or a repetitive peak as required by the applicable standard. Identify the circuits on both sides of the barrier and the intended basic, supplementary or reinforced insulation function.
Classify the environment and material
Pollution degree describes the relevant microenvironment rather than a general impression of room cleanliness. Coatings and enclosures may change the assessment only when the applicable rules permit them and the process is controlled. Material group depends on comparative tracking index evidence. Group I corresponds to CTI at least 600; II to 400–599; IIIa to 175–399; IIIb to 100–174. Verify the laminate certification instead of assuming all FR4 has one CTI.
Gather missing conditions before lookup
The checklist intentionally leaves numerical spacing unresolved. Clearance selection can depend on impulse withstand requirements, overvoltage category, field conditions and altitude correction. Creepage selection depends on working voltage, pollution degree and material group under the applicable insulation rules. Product standards can impose additional or different conditions. The entered voltage, pollution degree and material group are a record of the review starting point, not a safe-distance determination.
Inspect the assembled product
Check distances across solder joints, component bodies, slots, mounting hardware and board edges. A slot may alter a surface path only when its geometry satisfies the relevant requirements. Contamination, coating defects and conductive debris can invalidate an otherwise careful layout. Document the exact standard edition, selected tables, environmental assumptions and verification method. For medical or mains equipment, have a qualified compliance reviewer approve the barrier before design release and production testing.
Work from your project brief
Start by confirming the units shown beside each input. Enter the operating condition you expect in the finished product, then change one variable at a time so the effect stays clear. The plus and minus controls make small adjustments, while the slider is useful for a quick sensitivity sweep. Blank fields, impossible ranges and unsupported geometries stop the calculation instead of silently preserving a previous result. A unit change converts the displayed value while the underlying calculation keeps a consistent canonical unit system.
Keep a Circuit Edge board-review record
Use Copy Results for a design-review note, CSV for a calculation register, and Share Link to preserve the input values in the URL. Download PDF creates a local report with the inputs, outputs, formula and limitations. The exported estimate is only useful when its assumptions remain attached. Keep the board revision, stackup revision, supplier tolerances and applicable load or interface requirement in the same review record. A later fabrication change can invalidate an earlier calculation even if the calculator inputs have not changed.
Separate the displayed digits from project confidence
Several digits are displayed to make comparisons and unit conversions useful. Those digits do not imply matching physical accuracy. Manufacturing variation, environmental conditions and the simplicity of the selected model can dominate the final result. Round the chosen design requirement in a direction that preserves engineering margin, then agree the tolerance with your fabricator. Use prototype measurements and the relevant analysis tools when a small change would affect reliability, regulatory compliance or product performance.
Worked example
At 230 V, pollution degree 2 and group IIIa, numerical spacing remains unresolved until working-voltage definition, impulse category, altitude, insulation type and applicable product standard are known. Use the defaults as a reproducible starting point, then substitute your own board data. When comparing a manual calculation, keep dimensional units consistent and avoid rounding intermediate values. If your result differs, check the input definitions before changing the model or applying an unexplained correction factor.
Continue with our calculation methodology, fabrication review checklist and high-speed layout guide. For board-specific support, contact Circuit Edge Technologies.
Frequently asked questions
What does the clearance & creepage tool calculate?
Record the insulation questions that a Circuit Edge layout brief must resolve before numerical spacing can be approved. This is guidance, not an IEC table lookup or compliance calculator. No numerical safe spacing is generated. Confirm against the applicable edition of IEC 60664-1 and the relevant product standard.
Which formula does this calculator use?
Clearance is the shortest distance through air. Creepage is the shortest distance along an insulating surface. No universal voltage-only formula establishes either requirement. The Methodology page records the model and its limitations so that a design reviewer can reproduce the assumptions.
How should I check the input definitions?
Clearance is an air path and creepage is a surface path. They respond to different stresses and cannot be reduced to the same voltage-to-distance multiplier. A working voltage entry is only one part of the problem. Establish whether it is RMS, DC or a repetitive peak as required by the applicable standard. Identify the circuits on both sides of the barrier and the intended basic, supplementary or reinforced insulation function.
What is a useful worked example?
At 230 V, pollution degree 2 and group IIIa, numerical spacing remains unresolved until working-voltage definition, impulse category, altitude, insulation type and applicable product standard are known. This example is a starting point for checking units, not a universal production recommendation.
Can I use the result as a fabrication or compliance approval?
This is guidance, not an IEC table lookup or compliance calculator. No numerical safe spacing is generated. Confirm against the applicable edition of IEC 60664-1 and the relevant product standard. Obtain the required engineering and manufacturing review before releasing a critical design.
How can I save and share my calculation?
Copy Results includes the inputs, outputs and limitations. CSV provides a local record, while Download PDF creates a local engineering report. Share Link encodes the canonical input values in the URL. Anyone with the link can reproduce that input set.
What should I verify before design release?
Check distances across solder joints, component bodies, slots, mounting hardware and board edges. A slot may alter a surface path only when its geometry satisfies the relevant requirements. Contamination, coating defects and conductive debris can invalidate an otherwise careful layout. Document the exact standard edition, selected tables, environmental assumptions and verification method. For medical or mains equipment, have a qualified compliance reviewer approve the barrier before design release and production testing.
Inputs and related calculators
Working voltage, Pollution degree, Material group (CTI).