Conduit Fill Calculator
Check how full a conduit is with a set of wires.
Work It Out And Get Clear Answers
Check how full a conduit is with a set of wires.
Conduit Fill Estimator
Enter your numbers below for an instant estimate.
How It Works
Key concepts behind this calculator
Enter Values
Fill in each field with your own numbers.
Calculate
Press Calculate to see the result.
Review
Read the breakdown and the explanation.
Adjust
Change values to compare scenarios.
Conduit Fill Quick Guide
Typical values for reference.
| Number of wires | Wire area incl. insulation (mm²) | Conduit internal diameter (mm) | Conduit fill |
|---|---|---|---|
| 6 | 14.2 | 21.2 | 24.14% |
| 3 | 14.2 | 21.2 | 12.07% |
| 12 | 14.2 | 21.2 | 48.27% |
| 6 | 7.1 | 21.2 | 12.07% |
| 6 | 28.4 | 21.2 | 48.27% |
| Rule of thumb: check your inputs, use the result as a guide and round sensibly. | |||
Conduit Fill FAQ
Answers to common questions about this calculator.
Fill = total wire area ÷ conduit area. 40% is the usual limit for three or more wires.
It uses the default inputs shown and the formula described above. Change any value and press Calculate to see how the result moves.
It is an estimate based on the inputs you enter. Check real quotes, labels, product data or official guidance for important decisions.
Yes. Replace each input with your own figures and press Calculate to update the result.