1. Crimping Ethernet Cables
What is crimping an Ethernet cable?
Crimping an Ethernet cable is the process of attaching connectors onto
the ends of Ethernet cables. This process is also called ‘RJ45 crimping’
because RJ45 is the name of the connectors that are used for Ethernet
cables, and they are what is being crimped.
Setting up networks involves setting up long Ethernet cable connections
between different devices. Instead of buying premade Ethernet cables of
varying lengths (e.g. 5ft, 10ft, 50ft, etc.), it’s more practical to just have a
big spool of cabling that we can roll out and cut to the exact length we
Therefore we need to be able to attach RJ45 connectors to the ends of
these cut cables so that we can actually plug them in!
2. Crimping Kit
RJ45 Crimping Tool Cable Stripper
Cable strippers are used to take
off the protecting shielding
around cables and expose the
inner wires. You can also do the
same thing with a simple blade or
pair of scissors. The trickiest part
about stripping cables is trying to
avoid cutting the inner wires!
An RJ45 crimping tool is the most essential tool. Although
it’s technically possible to crimp Ethernet cables without
this specialized tool, it’s not very practical for crimping lots
Its primary utility is to do the actual ‘crimping’ part of
compressing/crimping the tiny gold pins in the RJ45
connector onto the Ethernet cables. It also has blades that
can be used to cut or strip wires.
3. RJ45 Connectors
RJ45 connectors are required for
crimping because they feature the 8
golden pins that get crimped onto
the 8 wires of the Ethernet cable.
They are what get plugged into
Ethernet ports! They also feature a
latch/clip that locks the Ethernet
cable into the port once it is
RJ45 boots can be optionally
used to protect the RJ45
connector. It provides insulation
and prevents the cable from
being breaking easily. They have
to put slipped onto the cable
before you put on the RJ45
4. RJ45 Cable Tester
RJ45 cable testers allow you to guarantee
that you did the job correctly!
They have two pieces that separate from
each other, and you plug each end of
your crimped Ethernet cable into the port
on each piece. Then you turn it on and
the cable tester will test the connection
for all 8 pins. If there are any missing
lights on any of the pins, it means that
you messed up somewhere and have to
5. How to Crimp an Ethernet Cable
Assuming you have a crimping kit and an Ethernet cable that
needs to be crimped, here are all the steps!
Step 0) Slip on the RJ45 boot (optional)
6. Step 1) Strip the cable
Push the cable into the razor slot of the strip tool and turn it around the cable to
make an even cut around the sheath. Careful not to nick the wires inside!
Unwrap the blue foil shielding and plastic to uncover the twisted wire pairs.
Push the copper grounding wire to the side. (Ignore the white string.)
7. Step 2) Organize the wires
In this step, you’ll be taking the 8 colored wires inside the
Ethernet cable and putting them into the correct ordering of
This is the hardest part of crimping! The wires are small and are
hard to control. Take your time and make sure you do this step
correctly! Otherwise you might have to go back and restart.
8. Step 2.1) Untwist the wires
There should be 4 pairs of wires: green, brown, orange, and blue.
Each pair has a solid-colored wire and a striped-colored wire.
Untwist these pairs and separate them into the 8 wires.
9. Step 2.2) Straighten out wires
After untwisting the wires, they are probably still kinked and
look like they want to be twisted. In this step, you should
carefully grab all the wires and try to straighten them out by
pulling on them. This will prevent the wires from moving
around later on.
Don’t break off the wires!
10. Step 2.3) Lay out wires in order
With your straightened out wires, put them into the
correct order! Make sure that the wires are all flat and in
line with each other.
The ordering for these wires is:
TIP After laying them out in order, straighten them out
again as a group! This will help keep the wires together.
11. Step 2.4) Trim the wires
Trim the wires evenly to about 1/2 inch in length using scissors or the
blade of your crimping tool. You want to make sure you have enough
room for the wires to reach the end of the RJ45 connector. But also try to
have room for the shielding of the cable to be inserted into the connector
TIP You can put the wires side-by-side to the RJ45 connector to see how
long you should cut it. Look at the next step to see what the final product
TIP If you don’t have the shielding inside of the connector, it makes it
easier for the wires to snap off later, which is bad.
TIP Make sure that you cut the wires evenly!
12. Step 3) Slide wires into RJ45 connector
Carefully slide your 8 wires into the connector. Make sure that the clip is facing away from you! If it
is really hard to slide it into the connector, you probably didn’t straighten out the wires enough in
step 2.2 or 2.3.
MORE INFO Inserting the wires with the clip facing away from you is the standard. However, you
could technically do it in ‘reverse’ and insert the wires with the clip facing you, as long as you do it
on both ends of the cable. You shouldn’t do this in practice though because others would get
confused when looking at your cable.
13. Step 4) Crimp it
Push the RJ45 connector into the slot of your crimping tool for RJ45 connectors. The
slot should be labeled something like “8P” for the 8-pin RJ45 connector that you’re
In this step, you’re doing the actual ‘crimping’ part and
crimping/compressing/stabbing the 8 golden pins on the RJ45 connector into the 8
TIP Squeeze as hard as you can! You need to make sure that all 8 pins are crimped.
14. Step 5) Test it Slide the two pieces of the tester apart and plug
each of the cable ends into either piece. Turn the
switch to “On” or “Slow.” If it’s working, all 8
numbers should be flashing green.
If any of them are not showing green, it means
something is wrong and you have to redo it! The
RJ45 connector can’t be reused once it’s
crimped, so you should just cut the end off and
start back at step 1.
If everything is green, then you’re done! If you
had a cable boot, you can push the boots onto
the RJ45 connector now.