WireGaugeCalc Free calculator · NEC cited · works offline
Bare Conductor Conduit Fill
Bare conductor conduit fill is fast with WireGaugeCalc, since you enter the conduit type, the bare wire size, and the count and the calculator returns the fill percent.
It uses the NEC Chapter 9 dimensions for bare conductors, so the area is smaller than an insulated wire of the same size.
You get a fill percentage checked against the 40% limit for the raceway.
Open the calculatorFill against NEC Chapter 9, Table 1 (40% for 3+ conductors) with Table 4 and Table 5 areas. Field aid only, verify against the current NEC and your local authority having jurisdiction.
Why Bare Conductor Area Differs In Conduit Fill
A bare conductor has no insulation, so its cross-sectional area is smaller than the same gauge insulated wire.
NEC Chapter 9 lists separate bare conductor dimensions, so the calculator uses those values rather than the insulated tables.
Smaller area means more bare conductors fit before the 40% fill limit is reached.
What WireGaugeCalc Checks For EMT, PVC, And RMC Fill
Bare conductor fill in a raceway depends on:
- Conduit type, such as EMT, PVC, or RMC
- Conduit trade size and its internal area
- Bare conductor area from NEC Chapter 9
- Number of bare conductors in the run
- The 40% fill limit for three or more conductors
One app for every NEC calculation
WireGaugeCalc keeps the calculations you reach for most in one place:
- Voltage drop and wire sizing for any run
- Conduit fill for EMT, PVC, and RMC
- Box fill and junction box sizing
- Ampacity and temperature derating
- Motor circuit and load calculations
- Conduit bend offsets and saddles
Built for the field, works offline
The whole app runs on your phone, so it keeps working in a basement, an attic, or a job site with no signal.
There is no account to create and nothing to load. Open it, run the number, and get back to work.
- No signup and no signal needed
- Answers in a tap, not a spreadsheet
- Same tool on phone, tablet, and desktop
Every result cites the NEC article
Each answer shows the table or formula it came from, so you can check the method and learn the code as you go.
That makes the app useful on the job and during exam prep, since the reasoning is right next to the number.
Switch the code year your job runs on
Jurisdictions adopt the NEC at different times, so you can match the calculation to the code in force:
- NEC 2017, 2020, and 2023 tables
- Copper and aluminum conductors
- 60, 75, and 90 degree C terminations
- Single-phase and three-phase systems
Run the number, then get back to work
Stop flipping through a paper book or hopping between calculator sites. Enter your values, read the code-cited answer, and move on. Free to use, no signup.
Open the calculatorFrequently asked questions
Does a bare conductor count toward conduit fill?
Yes, every conductor in the raceway counts toward fill, but a bare conductor uses its smaller bare area from NEC Chapter 9 rather than an insulated area. Verify the figures against the current NEC and your local authority having jurisdiction.
What fill percent applies to multiple conductors in EMT?
For three or more conductors in EMT, PVC, or RMC, the limit is 40% of the conduit internal area.
Is WireGaugeCalc free to use?
Yes. Every calculator is free to run with no signup. A paid tier adds saved projects, PDF reports, and extra code years, but the core math stays free.
Does it work without internet?
Yes. The app runs on your device, so it keeps working with no signal on a job site, in a basement, or in an attic.
Are the results code accurate?
Results follow published NEC tables and standard formulas, and each answer shows the article it came from. It is a field aid, not a stamp of approval, so verify against the current code and your local authority before you wire anything.
Which NEC code year does it use?
You can switch between NEC 2017, 2020, and 2023, since jurisdictions adopt the code at different times. Pick the year your job runs on.