How to Terminate Ethernet Cable: RJ45 Plugs and Keystone Jacks, Step by Step

Terminating your own Ethernet cable is one of the highest-leverage skills in home networking: bulk cable plus your own ends costs a fraction of pre-made patch cables at every custom length you'll ever need. It's also where most DIY networks quietly fail. Here's the method that passes testing the first time.

The two ways to terminate — and when each is right

There are two destinations for a cable end: an RJ45 plug (a male connector, for plugging straight into gear) and a keystone jack (a female socket that snaps into a wall plate or patch panel). The rule seasoned installers follow: permanent, in-wall runs end in keystone jacks; plugs are for patch cables between jack and device. Jacks are more forgiving to terminate, protect the solid-core cable from flexing, and leave you a clean wall plate instead of a cable dangling from drywall.

Tools worth owning

A crimper for RJ45 plugs, a punch-down tool for keystones (many jacks include a free plastic one that works fine), a cable jacket stripper, flush cutters, and — non-negotiable — a basic cable tester. A $15 tester turns "the internet feels flaky" into "pin 6 is open," which is the difference between five minutes and a lost weekend.

T568A or T568B? Pick B, stay consistent

Both wiring orders work identically; they're just color conventions for which wire lands on which pin. North American practice overwhelmingly uses T568B: white-orange, orange, white-green, blue, white-blue, green, white-brown, brown. What actually matters is using the same standard on both ends — mixing A and B by accident gives you a crossover cable and a head-scratching afternoon.

Terminating an RJ45 plug

Strip about an inch of jacket. Untwist each pair only as far as needed — the twist is the noise immunity, and Cat6/6A specs assume you preserve it to within half an inch of the plug. Arrange the eight wires in T568B order, flatten them into a ribbon, trim square, and slide into the plug until every wire hits the end wall — check the tips through the clear plastic. Crimp firmly once. With Cat6's thicker conductors and internal spline, pass-through style plugs (wires exit the front, crimper trims them) make the order-check dramatically easier and are what we'd hand a first-timer.

Punching down a keystone jack

Strip two inches of jacket, fan the pairs into the jack's color-coded slots (every jack is printed with both A and B maps — follow the B row), keep each wire's twist as close to the slot as possible, and punch down with the tool's cut side facing outward so it trims the excess flush. Snap the dust cap on, then the jack into its plate. No crimping skill involved — this is why pros put jacks on everything permanent.

The five classic failures

Untwisting too much (crosstalk, failed 10G), nicking conductors while stripping the jacket (intermittent opens), wrong wire order discovered after crimping (plugs are single-use — cut and redo), using solid-core bulk cable for flexing patch leads or stranded cable for punch-downs (each termination style expects one type — our solid vs stranded guide explains which), and skipping the tester. Test every run before you patch the drywall. Every single one.

Stock up on 1000 ft bulk boxes in Cat6 or Cat6A, and if you're planning the whole-house version of this project, start with our home network wiring plan and the companion piece on running cable through walls.