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Conduit Fill Calculator Tools
Don’t want to do manual calculations with the Conduit Fill Calculator? This free Conduit Fill Calculator is designed for electrical engineers and contractors. It offers fast online calculations and real-time feedback, improving your work efficiency. You can also copy results with one click. Try it now!
حاسبة ملء الأنابيب
Live conduit fill calculations. Default reference allowed fill: 1 conductor = 53%, 2 = 31%, 3+ = 40% — guidance only; verify local code.
Conduit
Conductor (single)
Allowed Fill / Options
⚠️Disclaimer (based on NEC reference)
This conduit fill calculator and tables are provided for informational and educational purposes only. All dimensions and conductor sizes are approximate and may vary by manufacturer. Results are based on general NEC (National Electrical Code) guidance (e.g., 53% for 1 conductor, 31% for 2 conductors, 40% for 3 or more), but local codes, standards, and engineering requirements may differ. This tool should not be used as a substitute for professional design, official NEC tables, or manufacturer specifications. Always verify conduit and conductor dimensions with certified data before installation. Use of this calculator is at the user’s own risk.
Extra Electrical Conduit Information
EMT & PVC Conduit Inner Diameter Table
| Trade Size | EMT Inner Diameter (in / mm) | PVC Sch 40 Inner Diameter (in / mm) | Cross-Sectional Area (in² / mm²) |
|---|---|---|---|
| 1/2″ | 0.622 in (15.8 mm) | 0.622 in (15.8 mm) | 0.304 in² (196 mm²) |
| 3/4″ | 0.824 in (20.9 mm) | 0.785 in (19.9 mm) | 0.534 in² (345 mm²) |
| 1″ | 1.049 in (26.6 mm) | 1.029 in (26.1 mm) | 0.865 in² (559 mm²) |
| 1-1/4″ | 1.380 in (35.0 mm) | 1.360 in (34.5 mm) | 1.497 in² (966 mm²) |
| 1-1/2″ | 1.610 in (40.9 mm) | 1.590 in (40.4 mm) | 2.036 in² (1,316 mm²) |
| 2″ | 2.067 in (52.5 mm) | 2.047 in (52.0 mm) | 3.357 in² (2,169 mm²) |
THHN OD Chart
| AWG Size | Conductor OD (in / mm) |
|---|---|
| 14 AWG | 0.111 in (2.82 mm) |
| 12 AWG | 0.130 in (3.30 mm) |
| 10 AWG | 0.164 in (4.17 mm) |
| 8 AWG | 0.216 in (5.49 mm) |
| 6 AWG | 0.262 in (6.65 mm) |
| 4 AWG | 0.333 in (8.46 mm) |
| 3 AWG | 0.346 in (8.79 mm) |
| 2 AWG | 0.384 in (9.75 mm) |
| 1 AWG | 0.431 in (10.95 mm) |
| 1/0 AWG | 0.484 in (12.29 mm) |
| 2/0 AWG | 0.530 in (13.46 mm) |
| 3/0 AWG | 0.585 in (14.86 mm) |
| 4/0 AWG | 0.646 in (16.40 mm) |
الأسئلة الشائعة
Conduit fill is the percentage of space inside a conduit occupied by conductors. Overfilling can cause overheating and make pulling wires difficult.
By comparing the cross-sectional area of all conductors to the available area of the conduit.
NEC recommends max fill: 53% for 1 conductor, 31% for 2 conductors, and 40% for 3 or more conductors.
Always use the insulated outside diameter for accuracy.
Yes, because the inner diameters differ by conduit type.
Yes, but you must calculate the area of each conductor separately and sum them.
Convert conductor and conduit diameters to the same unit system before calculating.
They are a general NEC guideline, but always confirm with local code or engineering requirements.
It may violate code, increase pulling tension, damage insulation, or cause overheating.
No — it’s a quick reference tool. Always verify with official code and manufacturer data.