ToolnozaENGINEERING TOOL
Conduit Fill Calculator
Calculate conduit fill percentage for multiple cable groups and the required internal diameter for your chosen limit.
Conduit Fill Calculator
FREE ONLINE TOOLSTEP BY STEP
How to use conduit fill calculator
- Check the input units and assumptions.
- Review the result and example.
IN PRACTICE
Example
3 cables of 8 mm OD in a 25 mm ID conduit: 30.72% fill; at a user limit of 40%, required ID = 21.91 mm.
GOOD TO KNOW
Which formula and assumptions are used?
Fill (%) = 100 × Σ(n × d²) / D²; required D = √(Σ(n × d²) / (limit / 100)). Uses cable outside diameter including insulation and conduit internal diameter. Fill limit is user supplied, not a code default. Area calculation does not verify pulling, bends, heat or local compliance.