How to Run Ethernet Cable Through Walls: DIY Wiring Guide

Running Ethernet cable through walls gives you a rock-solid wired connection that WiFi simply cannot match — no interference, no latency spikes, no dead zones. This DIY guide walks you through everything from choosing the right cable to fishing it cleanly through drywall.

Why Run Ethernet Instead of Using WiFi?

WiFi is convenient, but it has real limitations: signal degrades through walls, interference from neighboring networks causes slowdowns, and shared wireless bandwidth means every connected device takes a cut. A direct Ethernet run delivers full-duplex speeds, consistent LAN latency under 1 ms, and zero wireless interference. If you’ve been frustrated by random WiFi speed drops or lag during gaming and video calls, a wired connection is the permanent fix.

Step 1: Choose the Right Ethernet Cable

Before you drill a single hole, pick the right cable — you don’t want to rip open walls again in two years because you bought the wrong type.

Cat5e — Skip It for New Installations

Cat5e supports up to 1 Gbps at 100 MHz over 100 meters. It’s cheap and widely available, but with gigabit internet plans now standard and multi-gig becoming common, Cat5e offers no headroom for future-proofing. Avoid it for any new in-wall run.

Cat6 — The Sweet Spot for Most Homes

Cat6 runs at 250 MHz and supports 10 Gbps at distances up to 55 meters. For the typical home run of 30–40 meters, Cat6 delivers full 10 Gbps performance. It’s the recommended choice for nearly all residential DIY installs and costs only a few cents more per foot than Cat5e.

Cat6a — Best for Future-Proofing

Cat6a (Augmented) operates at 500 MHz and sustains 10 Gbps across the full 100-meter channel. It’s physically larger and stiffer than Cat6, which makes it harder to fish through tight bends, but it’s the best option if you want your wiring to last 15+ years without replacement.

Step 2: Gather Your Tools

Running cable through walls requires a few specialized items beyond a basic toolkit:

• Stud finder: Locate studs and — with better models — electrical wires and pipes behind the wall before drilling.
• Electric drill with paddle/spade bits: For boring clean holes through drywall and wood framing.
• Fish tape or fish sticks: A rigid steel or fiberglass tape that guides your cable through closed wall cavities.
• Keyhole/drywall saw: For cutting openings for wall plates at entry and exit points.
• Low-voltage mounting brackets and keystone jacks: For a clean, professional-looking termination at each end.
• RJ45 crimp tool and connectors (or punch-down tool): To terminate the cable.
• Cable tester: To verify all eight conductors are wired correctly before patching the wall.
• Masonry bits: Only needed if you’re drilling through concrete or brick.

Step 3: Plan and Execute the Cable Run

Map Your Route First

Trace the shortest path from your router to the destination room, noting every wall, floor, and ceiling you’ll cross. Rooms on the same floor sharing a wall are easiest — one hole per side and the cable runs horizontally through the wall cavity. Runs between floors require accessing the top or bottom plate of the wall framing, which takes more effort but follows the same principles.

Find Studs, Pipes, and Electrical Wires

Use a quality stud finder to map every obstacle along your planned route. Maintaining at least 2 inches of clearance from electrical wiring is both a safety requirement and a performance necessity — running Ethernet parallel to a live 120V circuit for more than a meter can induce interference that degrades your connection. If you must cross an electrical line, do it at a 90-degree angle to minimize electromagnetic coupling.

Drill Your Holes

Mark entry and exit points with a pencil, then drill a small pilot hole first to confirm the path is clear. Once confirmed, open the hole to your final diameter — a ¾-inch spade bit handles Cat6 cleanly. If routing between floors, you’ll need to bore through the sole plate (at the base of the wall) or the top plate (at the ceiling) using a long-shank drill bit.

Fish the Cable Through

Feed fish tape into one opening until it exits the other. Tape the end of your Ethernet cable securely to the fish tape — fold the cable back and wrap tightly with electrical tape to create a smooth nose that won’t snag on drywall edges or insulation. Pull the fish tape back through while feeding cable from the spool. In tight cavities with insulation, having a second person feed cable from one end while you pull from the other makes this step far easier.

Terminate, Test, and Patch

Terminate both ends into keystone jacks using a punch-down tool, or into RJ45 connectors using a crimp tool. Plug in your cable tester and verify all eight conductors light up in the correct T568B sequence. Once confirmed, install your low-voltage wall plates, patch any gaps in drywall, and connect your devices. Run a speed test to confirm you’re hitting expected throughput — a properly installed Cat6 run should deliver your ISP’s full plan speed with no overhead loss.

Tips for Concrete and Brick Walls

Masonry walls require hammer-drill bits and significantly more time. Aim to drill through mortar joints rather than the brick face — mortar is softer, less likely to crack, and easier to patch. Use a 10–12 mm masonry bit for a single-cable run, and install a rubber grommet at the hole edge to protect the cable sheath from abrasion.

Safety and Code Requirements

In-wall Ethernet cable is classified as low-voltage wiring (Class 2/3 under the National Electrical Code). For runs inside wall cavities between floors, use riser-rated (CMR) cable. If your route passes through a plenum space — the air-handling cavity above a drop ceiling — you must use plenum-rated (CMP) cable by code. Plenum cable produces far less toxic smoke in a fire and is required in most commercial and multi-unit residential buildings. Check local codes before starting work.

What Will It Cost?

For a typical single-room run of 15–30 meters, expect to spend $30–$60 on Cat6 cable plus $20–$50 on wall plates and keystone jacks. Fish tape runs $20–$50; a quality stud finder costs $25–$80. A complete first-time tool kit runs roughly $100–$150 — tools you’ll reuse for every future run. Professional installation typically adds $150–$300 per run depending on wall type and routing difficulty.

The Bottom Line

Running Ethernet through walls is a weekend DIY project that pays off for years. Use Cat6, plan your route carefully, locate every hazard before drilling, and always test before patching. The result is a connection that’s faster, more reliable, and lower latency than any wireless alternative. For the rooms where in-wall wiring isn’t practical, pair your wired backbone with a quality mesh WiFi system to cover the rest of your home.