WIRE
FILL
CHART
Free live wire fill chart and conduit fill calculator for US electricians, inspectors, and engineers. Pick a conduit. Add conductors. Read the fill percentage. Compute jam probability. All math straight from NFPA 70 (2023), Chapter 9, Tables 1 / 4 / 5. No signup. No ads on the tool.
- EMT · IMC · RMC · PVC 40 · PVC 80 · FMC · LFNC · ENT
- THHN · THWN-2 · XHHW · RHH · RHW · TW
- Live fill % · NEC-status callout · jam analysis
- Auto-recommend next trade size on overfill
- CONDUCTORS
- 3
- WIRE AREA
- 0.040in²
- CONDUIT AREA
- 0.304in²
- JAM RISK
- LOW
- Three or more conductors — NEC allows 40% fill.
HOW THE WIRE FILL CHART IS COMPUTED
Every cell of every wire fill chart on this site is one division — total conductor area divided by conduit interior area, compared to a NEC fill cap.
From NEC Chapter 9, Table 4. A 3/4" EMT has 0.533 in² of interior cross-section.
From NEC Chapter 9, Table 5. Each conductor's area times its count. Sum every row.
Compare against NEC Table 1: 53% (1), 31% (2), 40% (3+).
EMT WIRE FILL CHART
Most-used slice of the full EMT × THHN / THWN-2 / XHHW reference. Counts are the maximum conductors per NEC fill limit.
| EMT → WIRE ↓ | 1/2" | 3/4" | 1" | 1-1/4" | 1-1/2" | 2" | 2-1/2" | 3" | 3-1/2" | 4" |
|---|---|---|---|---|---|---|---|---|---|---|
| 14 AWG | 12 | 22 | 35 | 61 | 84 | 138 | 241 | 364 | 476 | 608 |
| 12 AWG | 9 | 16 | 26 | 45 | 61 | 101 | 176 | 266 | 347 | 443 |
| 10 AWG | 5 | 10 | 16 | 28 | 38 | 63 | 111 | 167 | 219 | 279 |
| 8 AWG | 3 | 6 | 9 | 16 | 22 | 36 | 64 | 96 | 126 | 161 |
| 6 AWG | 2 | 4 | 7 | 12 | 16 | 26 | 46 | 69 | 91 | 116 |
| 4 AWG | — | 2 | 4 | 7 | 10 | 16 | 28 | 43 | 56 | 71 |
| 3 AWG | 1 | — | 3 | 6 | 8 | 13 | 24 | 36 | 47 | 60 |
| 2 AWG | 1 | — | 3 | 5 | 7 | 11 | 20 | 30 | 40 | 51 |
| 1 AWG | 1 | — | — | 4 | 5 | 8 | 15 | 22 | 29 | 37 |
| 1/0 | 1 | 1 | — | 3 | 4 | 7 | 12 | 19 | 25 | 32 |
| 2/0 | — | 1 | — | 2 | 3 | 6 | 10 | 16 | 20 | 26 |
| 3/0 | — | 1 | 1 | — | 3 | 5 | 8 | 13 | 17 | 22 |
| 4/0 | — | 1 | 1 | — | 2 | 4 | 7 | 11 | 14 | 18 |
MORE CALCULATORS
Pair the conduit fill calculator with the rest of the WireFillChart toolkit.
ALL WIRE FILL CHARTS
Sortable, filterable, printable wire fill chart references — every conduit type, every common insulation.
DIRECT-ANSWER LIBRARY
Pre-computed NEC fill pages for the most-searched wire-in-conduit combinations.
Conduit Fill by Size
Every trade size of EMT, Rigid (RMC), PVC-40 and FMC — max-wires tables with the exact NEC Table 4 area.
How Many … in …
Direct answers: "how many #12 THHN in 3/4" EMT?" — with the worked math and a step-up / step-down comparison.
Romex / NM in Conduit
Smallest EMT / Rigid / PVC / Flex for 14-2 through 6-3 NM-B, plus MC and UF-B — Chapter 9 Table 1 Note 9.
WIRE FILL CHART · FAQ
Eight common questions about the wire fill chart and NEC conduit fill rules. Answer drawer reveals on click.
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WIRE FILL CHART
The calculator runs entirely in your browser. Nothing to install. Save the page, print the EMT chart, head into the field. All NEC 2023 wire fill chart math — free, forever.