Cat6 & Cat6a Conduit Fill Chart
How many Cat5e, Cat6, and Cat6a cables fit in EMT, PVC, rigid, and flex conduit — using typical UTP outside diameters and the NEC 2023 Chapter 9 raceway fill limits.
DATA CABLE FILL BY CONDUIT
Pick a conduit type — counts update for Cat5e, Cat6, Cat6a (UTP) and shielded Cat6a.
| Trade size ↓ | Cat5e 0.2" OD | Cat6 0.23" OD | Cat6a 0.3" OD | Cat6a STP 0.33" OD |
|---|---|---|---|---|
| 1/2" EMT | 3 | 2 | 1 | 1 |
| 3/4" EMT | 6 | 5 | 3 | 1 |
| 1" EMT | 11 | 8 | 4 | 4 |
| 1-1/4" EMT | 19 | 14 | 8 | 6 |
| 1-1/2" EMT | 25 | 19 | 11 | 9 |
| 2" EMT | 42 | 32 | 18 | 15 |
| 2-1/2" EMT | 74 | 56 | 33 | 27 |
| 3" EMT | 112 | 85 | 50 | 41 |
| 3-1/2" EMT | 146 | 111 | 65 | 53 |
| 4" EMT | 187 | 142 | 83 | 68 |
Typical UTP OD · NEC 2023 Ch.9 fill (53 % / 31 % / 40 %) · verify your cable's datasheet OD
How data cable conduit fill works
Communications cables in a raceway use the same NEC Chapter 9, Table 1 percentages as power conductors — 53% for a single cable, 31% for two, and 40% for three or more. The difference is the area you plug in: instead of an NEC-tabulated insulated area, you use the cable's round outside cross-section, π × (OD ÷ 2)². A 0.23 in Cat6 is 0.0416 in²; a 0.30 in Cat6a is 0.0707 in². Divide the conduit's 40% area by that figure and round down.
Why the outside diameter is the whole game
Because fill area scales with the squareof diameter, small OD differences matter a lot. Cat6a UTP is typically 0.27–0.35 in versus 0.21–0.25 in for Cat6 — so a conduit that swallows a dozen Cat6 may only take six or seven Cat6a. Shielded (F/UTP) Cat6a is fatter still. That is why this chart shows four columns, and why you should confirm the actual OD printed on your cable's datasheet before committing to a conduit size.
Pull tension and bend radius — the real limit
Data cable is far more fragile than THHN. Two limits usually bind before the fill percentage does:
- Pull tension: TIA guidance caps UTP at about 25 lbf (110 N). Overpulling untwists the pairs and raises NEXT/insertion loss — the link can fail certification even though nothing looks damaged.
- Bend radius: keep installation bends at 4× the cable OD (about 1 in for Cat6). Tight 90° LBs and back-to-back bends are the usual culprits.
- Heat & PoE: tightly packed bundles carrying PoE run hotter; many installers cap data conduits at ~40% and derate large PoE bundles regardless of fill.
For those reasons most low-voltage installers fill data conduit more conservatively than the raw 40% number — leaving room to add a run later and to keep pulls easy. For power conductors instead, use the conduit fill calculator or the EMT fill chart.
Separation from power
Fill is only half the job: the NEC and TIA-569 also want communications cable kept away from parallel power runs (commonly 2–12 in depending on the power circuit) and generally in a separate raceway from line-voltage conductors. Sharing a conduit with power wiring is restricted — check NEC Article 800/805 and your local rules before combining them.
FREQUENTLY ASKED QUESTIONS
Conduit interior areas are NEC 2023 (NFPA 70) Chapter 9, Table 4; fill percentages are Chapter 9, Table 1. Cable outside diameters are typical industry values for UTP/shielded construction, not NEC-defined — verify your product datasheet. Pull-tension and bend-radius figures follow TIA/EIA structured-cabling guidance. WireFillChart is an independent reference, not affiliated with NFPA or TIA. Verify against the code edition adopted by your local authority having jurisdiction (AHJ).