WireGaugeCalc Free calculator · NEC cited · works offline
Conduit Stuff Calculater
Conduit stuff calculater is fast with WireGaugeCalc, since you pick the trade size and conductors and the app returns the fill percentage.
The calculator uses the NEC Chapter 9 tables, so a run with three or more conductors is held to the 40% fill limit.
You see whether the EMT or PVC has room before you start the pull, so you size the conduit once.
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 Conduit Fill Is Counted
Fill is the total conductor cross section compared to the inside area of the raceway.
WireGaugeCalc sums each conductor area and reports the percentage, so an over-fill shows before you pull wire.
Since the 40% limit covers three or more conductors, the app applies it to your EMT, PVC, or RMC run.
Sizing EMT And PVC Raceway
The calculator covers the inputs that decide conduit fill:
- EMT, PVC, and RMC trade sizes
- Conductor count and gauge per Chapter 9
- 40% fill limit for three or more conductors
- Insulation type for the correct conductor area
- Pass or over-fill result for the run
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
How many THHN conductors fit in 3/4 inch EMT?
It depends on gauge, but 3/4 inch EMT holds several 12 AWG THHN conductors within the 40% limit. Confirm the count against the current NEC Chapter 9 tables and your local authority having jurisdiction.
Is the fill limit different for two conductors?
Yes, two conductors allow 31% fill and one allows 53%, while three or more use the 40% limit, and the calculator applies the right value for your count.
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.