WireGaugeCalc Free calculator · NEC cited · works offline
1.5in Conduit
1.5in conduit fill is quick with WireGaugeCalc, which checks how many conductors fit inside a 1-1/2 inch raceway under NEC Chapter 9.
You choose the conduit type, the wire size, and the conductor count, and the tool compares total wire area to the allowable fill.
So you know the run passes the 40 percent limit before you start pulling.
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 Fill Is Figured For EMT, PVC, And RMC
Conduit fill compares the cross-sectional area of your conductors to the internal area of the raceway, since NEC Chapter 9 sets a percentage cap on how full it can be.
Three or more conductors are limited to 40 percent fill, and the internal area differs between EMT, PVC, and RMC even at the same trade size.
The tool reads the Chapter 9 tables so each 1-1/2 inch run is checked against the correct numbers.
What Affects The Conduit Fill
Several factors decide whether the conductors fit:
- Conduit type, since EMT, PVC, and RMC have different inside diameters
- Conductor count, because three or more caps fill at 40 percent
- Insulation type, as THHN and XHHW have different cross-sections
- Wire gauge, which sets the area each conductor takes
- Grounds and neutrals, which all count toward the total fill
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 1.5 inch EMT?
At 40 percent fill, 1-1/2 inch EMT holds many 12 AWG THHN conductors, but the exact count depends on wire size and type. Confirm the result against the current NEC Chapter 9 tables and your local authority having jurisdiction.
Does 1.5 inch PVC hold the same as 1.5 inch EMT?
No. PVC, EMT, and RMC have different internal areas at the same trade size, so the allowable conductor count changes with the raceway type.
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.