WireGaugeCalc Free calculator · NEC cited · works offline
Conduit Calculator
Conduit calculator is fast with WireGaugeCalc, since you pick the raceway type and trade size and it returns the fill percentage right away.
Enter each conductor size and count, and the tool totals their cross-sectional area against the conduit's interior area.
You get a clear pass or fail before you cut a single stick of pipe.
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.
A cables in conduit calculator that follows Chapter 9
The tool reads conductor areas from NEC Chapter 9 tables, so the math matches the code book.
It applies the 40 percent fill limit for three or more conductors, since that is where most runs land.
Pulling within that limit lowers friction and protects the insulation as you feed the wire.
Size EMT, PVC, and RMC without guessing
WireGaugeCalc covers the common raceways you bend and glue every day:
- EMT, PVC, and RMC trade sizes from 1/2 inch up
- 40 percent fill for three or more conductors
- 31 percent fill for two conductors, 53 percent for one
- Mixed conductor sizes in a single run
- Total fill percentage and remaining capacity
- Pass or fail flag for the chosen pipe
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
Why is the fill limit 40 percent for most runs?
NEC Chapter 9, Table 1 sets 40 percent fill for three or more conductors so the wire pulls without damaging the insulation. The figure drops to 31 percent for two conductors and 53 percent for one. Always verify the current NEC and your local authority having jurisdiction before the final pull.
Does the conduit type change how many cables fit?
Yes. EMT, PVC, and RMC of the same trade size have different interior areas, so this cables in conduit calculator uses the correct area for each one before applying the fill percentage.
Do equipment grounding conductors count toward fill?
Yes, every conductor in the raceway counts, including grounds. Add each one so the total area reflects the real pull.
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.