Conduit Fill Calculator

Conduit Fill Calculator checks whether a conductor bundle fits a raceway, or finds the smallest trade size that will hold it, against NEC Chapter 9 tables.

Use this conduit fill calculator to check fill percentage for EMT, IMC, RMC, or PVC raceway, or to find the minimum trade size for a bundle of conductors, using NEC Chapter 9 Table 1, Table 4, and Table 5 data. Every area figure applied to your bundle is shown on screen so you can check the math.

FILL
- Pick a raceway type and trade size, and toggle the Note 4 nipple exception for a raceway 24 inches or less
- Build a mixed conductor bundle: add rows of insulation type, conductor size, and quantity
- See fill percentage against the applicable limit as you edit, with a gauge showing where you sit against the 53%/31%/40%/60% bands
- See total conductor area, allowed area, and conduit total area
- Save the current bundle and raceway as a pull; the first saved pull needs no ad

CONDUIT
- Enter a conductor bundle and get the smallest verified trade size of the selected raceway type that stays within the NEC Chapter 9, Table 1 fill limit
- See the next trade size up as headroom for a run that may be pulled again
- Review the saved bundle summary with one tap back to editing it
- View your saved pulls; saving needs no ad, and the list unlocks with a short rewarded ad

PULLS
- Save a named raceway-and-bundle combination for repeat use
- Reload a saved bundle into the Fill screen in one tap
- Delete any saved bundle
- The first saved bundle needs no ad; saving more unlocks with a short rewarded ad

WHAT IT CALCULATES
This app implements NEC Chapter 9 Table 1 fill-limit percentages (which depend on conductor count, not on how full the raceway looks), Table 4 conduit interior areas for EMT, IMC, RMC, and PVC Schedule 40/80, and Table 5 conductor areas for THHN/THWN-2, XHHW-2, and TW insulation. It is a calculation aid, not a substitute for the authority having jurisdiction or the code edition actually adopted for an installation, which governs.

BUILT FOR THE JOB SITE
- Fast entry with minimal taps
- Works offline on site
- No account required
- Your saved pulls and bundles stay on your device

This app is ad-supported. Fill and sizing calculations are always available; saving beyond the first pull or bundle unlocks with a short rewarded ad.