Inputs
Conduit & Conductors
White theme
Per-row “Area each” can be entered in in² or mm².
| AWG / kcmil | Insulation Library | Qty | Area each (row units) | Total (in²) | |
|---|---|---|---|---|---|
Example data
Click Load example above to prefill with #12 THHN ×4 and #10 THHN ×2, then run compute.
| Conduit | Size | Wires | Used Area (in²) | Allowed Area (in²) | Fill % | Status |
|---|---|---|---|---|---|---|
| EMT | 1" | #12 THHN ×4; #10 THHN ×2 | 0.095 | 0.346 (40% of 0.864) | 27.5% | OK |
Formula used
Fill factor: If total conductors = 1 → 53%; = 2 → 31%; ≥ 3 → 40%. If “Nipple ≤ 24 in.” is enabled, 60% applies.
- Sum of conductor areas = Σ(areaeach × qty).
- Allowed area = fill factor × conduit internal area.
- Fill % = 100 × used area ÷ allowed area.
- Pass if used area ≤ allowed area.
Libraries: THHN/THWN‑2 baseline, XHHW‑2 (approx +12%), Compact THHN (approx −8%). For datasheet values or cable assemblies, choose “Other/custom” and enter an area in your preferred row unit.
How to use
- Choose the conduit type. Pick “check fill” for a specific size or “suggest minimum size.”
- Toggle “Nipple ≤ 24 in.” only when the run length qualifies.
- Add conductor groups. For custom entries, choose a row unit (in² or mm²).
- Click Compute. Review used area, allowed area, and pass/fail.
- Use Suggest minimum size to find the smallest trade size that passes.
- Export your result as CSV or PDF. Lock output units for consistent reports.
FAQs
Yes. Use the row unit selector to switch to mm², then type the datasheet area. The calculator converts to in² internally.
Yes for display. Library areas are computed from the selected AWG/kcmil and library in in²; the input shows the converted value if you switch the row unit.
THHN/THWN‑2 baseline, XHHW‑2 (approx +12%), Compact THHN (approx −8%), and a Custom option where you can enter a specific area from a datasheet.
Yes. Select a unit and check “Lock units.” Your preference is saved locally and restored automatically next time.
Values align with common Chapter 9 tables for conduit and conductor areas. Always confirm your jurisdiction’s adopted edition and any local amendments before construction.
The XHHW‑2 and Compact THHN libraries apply ±12%/−8% multipliers to THHN areas as practical approximations. For critical work, replace with manufacturer values using the Custom option.
Output
Results
Run the calculation to see results.