LED strips rarely come in exactly the length your shelf, ceiling cove or TV needs. Good news: learning how to cut LED strip lights takes about thirty seconds, and the strip keeps working on both sides of the cut as long as you snip in the right place.
The trickier part is joining pieces back together around corners and across gaps. This guide covers where to cut, which connector to use, how to solder when connectors won't do, and how to keep long runs evenly bright.
Know your strip before you cut
Look closely at the strip and note three things.
Voltage
Strips are commonly 5 V, 12 V or 24 V. The voltage is usually printed on the strip itself or the reel. It decides how often you can cut and how long a run can be before it dims.
Number of pads
| Strip type | Pads | Typical labels |
|---|---|---|
| Single color | 2 | + and − |
| RGB | 4 | +, R, G, B |
| RGBW | 5 | +, R, G, B, W |
| RGB + tunable white | 6 | +, R, G, B, WW, CW |
| Addressable (pixel) | 3 | 5V or 12V, Data, GND |
Width and type
Common widths are 8 mm, 10 mm and 12 mm. Note whether the strip is bare (indoor), silicone-coated or sealed in a tube (waterproof), and whether it uses individual SMD chips or a continuous COB line. Connectors are sold by width and pin count, so you need all three facts.
How to cut LED strip lights in the right place
Every strip is divided into short segments. Each segment ends at a pair (or row) of copper pads, usually marked with a thin line or a small scissors icon. That is the only place to cut.
- 5 V strips can often be cut every 1 to 3 LEDs.
- 12 V strips are usually cut every 3 LEDs, roughly every 2 inches (5 cm) on a 60-LED-per-meter strip.
- 24 V strips are usually cut every 6 LEDs, roughly every 4 inches (10 cm).
- COB strips have cut marks every inch or two, depending on the model.
Unplug and measure
Disconnect power. Measure the space, then find the nearest cut mark that fits. Rounding down is better than leaving a dead stub hanging past the edge.
Cut straight through the middle of the pads
Use sharp scissors or flush cutters and cut down the center line so each side keeps half of every copper pad.
Test both pieces
Plug in the piece still attached to the power lead. The offcut works too; it just needs its own connection.
Use the calculator to plan length and power
Before cutting, it helps to know your total run length and whether your power supply can handle it. Enter your measurements in the calculator below to get the strip length, wattage and a suggested power supply size with headroom.
LED strip length and power supply calculator
Size the power supply, find the cut interval and see whether a long run needs power injection.
Each block in the preview is one powered section. Always check the watts-per-meter on your strip's label; it varies by brand.
Connect LED strip lights with solderless connectors
Clip-on connectors are the easiest way to join pieces. They have small metal teeth or contacts that press onto the copper pads when you snap the lid shut.
Types you'll see
- Strip-to-strip: joins two pieces end to end.
- Strip-to-wire (gap connector): two clips linked by a short cable to bridge a doorway, a cabinet gap or a window.
- L-shaped: a rigid 90-degree corner.
- T and X shapes: split one run into branches.
- Power pigtail: a clip with a barrel jack to feed power into any cut end.
Getting a solid connection
Peel back the adhesive
Lift about half an inch of backing tape so the strip sits flat inside the clip.
Line up the polarity
Match + to + and each color letter to its twin. On addressable strips, follow the arrows; data only flows one direction.
Slide in fully and close
Push the strip until the pads sit under the contacts, then press the lid until it clicks.
Test, then stick
Power on and check every color before peeling the rest of the backing.
How to turn corners
You have three ways to get around a corner.
- Fold it. For single-color and RGB strips, you can fold the strip back on itself to make a neat 90-degree turn without cutting. Fold at a gap between LEDs, never across a chip, and don't crease it repeatedly.
- L connector. Cut at the corner and snap both ends into a rigid L. Clean, but it adds a little bulk.
- Gap connector. A wired connector gives you any angle and works for inside corners, outside corners and ceiling-to-wall turns.
Side-bend (S-shaped) strips are made to curve sideways, which is handy for rounded mirrors and signs.
Soldering: the most reliable joint
Clips are convenient but can loosen with vibration or heat. For permanent installs, cove lighting or anything hard to reach later, solder.
- Soldering iron, around 30–60 W, set roughly 320–370 °C
- Rosin-core solder, thin gauge
- Stranded wire, 20–22 AWG for most strip runs
- Heat-shrink tubing and a heat gun or lighter
- Small clamp or helping hands
Tin each pad with a small blob of solder, then tin the stripped wire ends. Hold each wire on its pad and touch the iron for a second or two until both flow together. Keep the heat brief; the pads can lift if you linger. Slide heat shrink over the joint for strain relief and insulation.
Waterproof strips and long runs
Sealing waterproof strips
To connect a silicone-coated strip, carefully slice away the coating above the pads with a craft knife. After joining, seal the end with a silicone end cap filled with neutral-cure silicone. An open cut end is no longer waterproof, even on an IP65 or IP67 strip.
Power injection
Voltage drops along a strip, so the far end of a long run looks dimmer or shifts color. A 12 V strip typically shows this beyond about 5 meters (16 feet). Fix it by running a second pair of wires from the power supply to the far end, or to the middle, so power arrives from two directions. A 24 V strip can run farther before dimming, which makes it the better pick for long coves.
Never chain several 5-meter reels end to end from a single feed. Even if the power supply is big enough, the thin copper traces on the first reel would carry the current for all of them and can overheat. Instead, run separate wire leads from the supply to the start of each reel, like spokes from a hub. Size the power supply about 20% above the total wattage so it runs cool.
Wrap-up
Cut on the marks, match polarity, test before sticking, and feed power from both ends on long runs. Next steps: compare strip types in our best strip lights for DIY projects guide, add voice control with our Alexa setup tutorial, or find the right smart LED strip lights and Wi-Fi LED controller for your project.
