WireGaugeCalc Free calculator · NEC cited · works offline
Pvc Conduit Fill
Pvc conduit fill is fast with WireGaugeCalc, since you pick the PVC trade size, enter your conductors, and read the fill percentage instantly.
The calculator pulls the conductor areas and raceway areas from NEC Chapter 9, so the math behind your fill number matches the code tables.
You get a clear yes or no on whether the run is legal before you ever pull a single wire.
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.
How WireGaugeCalc checks your PVC fill against Chapter 9
The 40 percent fill limit applies to any raceway carrying three or more conductors, so the tool flags a run as soon as it crosses that line.
Each conductor takes its area from the insulation type you choose, since THHN and XHHW occupy different space inside the same PVC.
The result is a fill percentage you can hand to an inspector without redoing the table lookup by hand.
What goes into a correct PVC conduit fill
Accurate fill depends on a few inputs you control on every job:
- PVC trade size, such as 3/4 inch or 1 inch Schedule 40
- Conductor count, since three or more conductors caps fill at 40 percent
- Insulation type per wire, because area differs by THHN, THWN, or XHHW
- Mixed sizes in the same run, which the tool totals together
- Spare capacity, so you can plan room for future adds
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
What fill percentage is allowed for PVC with three or more conductors?
The limit is 40 percent of the conduit's internal area for three or more conductors. WireGaugeCalc compares your total conductor area to that 40 percent value and tells you if you pass.
Does Schedule 40 PVC hold the same number of wires as Schedule 80?
No, Schedule 80 has a thicker wall and a smaller inside area, so it fits fewer conductors at the same trade size. Always confirm the exact area against the current NEC Chapter 9 tables and your local authority having jurisdiction.
Can I mix different wire sizes in one PVC run?
Yes, you can mix sizes as long as the combined conductor area stays at or under the 40 percent fill. The calculator adds up each conductor's area so the total is correct.
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.