Walk past a modern retail display, a hotel cove ceiling or a well-designed kitchen island, and you'll notice something about the lighting: there are no visible dots. The light is a single unbroken line, evenly bright from end to end, with no bright points and no dark gaps between them.
That effect comes from COB LED strip lights — a construction that replaced individual surface-mounted LEDs with a continuous phosphor layer. Over the past few years COB has moved from a specialist product to the default choice for any application where the strip is visible or where light quality matters.
This guide covers what COB actually is, how it differs from SMD LED tape, and how to choose the right density, color temperature, CRI and voltage for your project.
What Does COB Mean?
COB stands for Chip on Board. In a conventional SMD LED strip, individual LED packages — SMD 2835, SMD 2025, SMD 5050 and so on — are soldered onto the PCB at regular intervals, each one a discrete point of light. The eye perceives each package as a separate dot, particularly when the strip is viewed directly or reflected off a glossy surface.
COB construction works differently. Hundreds of bare LED dies are bonded directly to the circuit board, then covered with a continuous layer of phosphor. There are no individual packages, no visible spacing, no separate points of light. The result is a uniform luminous line rather than a row of dots.
This is why COB LED strip lights are frequently sold as dotless LED strip lights or continuous LED strip lighting — the terms describe the same construction from the perspective of what you actually see.
COB vs SMD: The Practical Differences
Both technologies produce white light from LEDs on a flexible PCB. The differences show up in how that light appears and behaves.
| COB LED Strip | SMD LED Strip | |
|---|---|---|
| Appearance | Continuous, dotless line | Visible individual LED points |
| LED count | 300–500+ dies per meter | 60–360 packages per meter |
| Beam angle | ~180° wide, diffuse | ~120° typical, more directional |
| Heat distribution | Spread across the full board | Concentrated at each package |
| Bending | Flexes smoothly along the length | Bends between LED positions |
| Diffuser requirement | Usually unnecessary | Often needed to hide dots |
| Cost | Moderately higher | Lower |
Appearance
This is the difference most buyers notice first. An SMD strip mounted in an open channel or behind a clear cover shows a visible row of bright points. Behind a frosted diffuser those points blur into a line, but the diffuser costs light output — typically 20–30% depending on the material.
COB strips produce a continuous line without a diffuser. In an aluminum channel with a clear cover, the output stays smooth. That means you keep the lumens the diffuser would have absorbed.
Beam Angle and Light Quality
COB strips typically emit across roughly 180 degrees, versus about 120 degrees for standard SMD packages. The wider, more diffuse spread reduces glare and produces softer shadow edges. In cove lighting, that wider spread washes the ceiling or wall more evenly. In under-cabinet applications, it reduces the harsh striping that SMD strips can cast onto a countertop.
Thermal Behavior
In an SMD strip, heat is generated at each individual package and must conduct away through a small solder contact area. In a COB strip, the dies are bonded across the full width of the board, spreading heat over a much larger surface. This generally means more stable operating temperatures and better lumen maintenance over time, particularly in enclosed channels.
Where SMD Still Wins
COB is not automatically the right choice. SMD strips remain preferable when:
- The strip will be fully concealed and dot visibility is irrelevant
- Budget is the deciding constraint on a large-quantity project
- The application needs a very narrow PCB (2.6mm–5mm ultra-narrow strips are almost exclusively SMD)
- You need very specific single colors — red, blue, amber — where SMD offers a wider range
For fixed-color and ultra-narrow applications, see Single Color LED Strip Lights.
Understanding COB LED Density
COB strip density is measured in LEDs per meter, the same as SMD. But the number means something different — it counts the individual dies bonded to the board, not visible packages. A 480 LEDs/m COB strip does not look four times "dottier" than a 120 LEDs/m SMD strip — the continuous phosphor layer means there are no discrete points to count in the first place.
Density affects three things: uniformity, output and cut interval.
312 LEDs/m
A balanced density that produces a fully continuous appearance while keeping the cut interval usefully short. On one 312 LEDs/m model the cut points fall roughly every 19mm at 12V and every 38mm at 24V. Cut spacing varies by SKU, so always check the figure on the specific product page rather than assuming a value for the density.
This density typically runs around 11W/m, delivering solid output for under-cabinet, cove and general accent lighting.
320 LEDs/m
Similar uniformity at a slightly lower power draw — around 8W/m. The lower wattage means less heat and lower driver capacity requirements, which makes this a practical choice for longer runs on a single driver or for applications where the lighting is on continuously.
On one 320 LEDs/m model the cut points fall every 25mm at 12V and every 50mm at 24V — again, confirm the exact spacing on the product page for the SKU you are buying.
384 LEDs/m
Higher die count produces an even smoother surface, particularly noticeable when the strip is viewed directly or through a clear cover at close range. Around 10W/m.
Higher-density COB strips at this level are often specified as 24V-only. The reason is practical: at higher wattage per meter, 12V operation would draw enough current to cause visible voltage drop well before the useful run length is reached. 24V halves the current at the same power, which is why many high-density COB strips skip 12V entirely.
480 LEDs/m
The highest common COB density, producing the smoothest possible surface. At around 10.5W/m the output is high and the appearance is completely uniform even under close inspection.
This density is the choice for display cases, museum vitrines, high-end retail and any application where the strip is directly visible and the light must be flawless.
Color Temperature: Choosing the Right CCT
COB LED strips are available across the same CCT range as SMD white strips. The choice follows the same logic — match the light appearance to the space and the activity.
- 2700K warm white — soft and amber-inflected, close to traditional incandescent. The standard choice for residential living spaces, bedrooms, restaurants and hospitality interiors where a relaxed atmosphere is the goal.
- 3000K warm white — slightly cleaner than 2700K while still reading as warm. The most widely specified CCT for residential kitchens, under-cabinet lighting and retail environments with warm-toned merchandise.
- 3500K neutral white — a genuinely neutral point between warm and cool. Useful in mixed-use spaces and in commercial environments where neither a warm nor cool bias is wanted. Not every COB strip offers 3500K, so check the CCT options on the specific product page.
- 4000K cool white — clean and high-contrast without being clinical. Common in offices, commercial kitchens, garages and task-lighting applications.
- 6000K daylight — crisp and blue-shifted. Suited to workshops, inspection areas, garages and commercial spaces that want a bright, cool-white appearance. Note that colour temperature describes the appearance of the white light, not how accurately it renders colour — if accurate colour judgment is the requirement, that is a CRI and TM-30 question, and a high-CRI 4000K strip will outperform a low-CRI 6000K one.
One point worth clearing up: dimming a standard COB strip does not change its colour temperature. PWM dimming switches the LEDs on and off rapidly at their nominal drive current and varies only the duty cycle, so a 3000K strip stays at 3000K whether it runs at 100% or 10%. Incandescent lamps warm as they dim; constant-voltage LED strips do not. If you specifically want output that warms as it dims, that requires a purpose-built warm-dim (dim-to-warm) product, which is a different construction — not something achieved with a standard strip and a dimmer.
CRI: Why COB Strips Usually Score Higher
CRI (Color Rendering Index) measures how accurately a light source renders color compared to natural daylight, on a 0–100 scale.
A common misconception is that COB construction delivers higher CRI by itself. It does not. CRI depends on the LED die, the phosphor formulation and the binning the manufacturer selected — not on whether the dies sit under a continuous phosphor layer or inside individual SMD packages. Plenty of COB strips are CRI 80, and plenty of SMD strips are CRI 95. Check the rated CRI for the exact product rather than inferring it from the construction.
What is true is that COB strips are more often positioned as premium products, so CRI 90+ is common in the category. That is a market pattern, not a physical property.
The practical difference between CRI 80 and CRI 90+ is significant in specific contexts:
- Retail merchandise — apparel colors, cosmetics, packaging, food. Under CRI 80 light, reds flatten toward orange and the merchandise looks duller than it is.
- Food service and display — meat, produce and baked goods look markedly better under high-CRI light. This is not a marketing claim; it is why supermarkets specify high-CRI fixtures over fresh food.
- Art, galleries and museums — accurate color rendition is the entire point.
- Beauty, salon and mirror lighting — skin tones under low-CRI light look sallow and uneven.
- Residential living spaces — high CRI makes wood, textiles and paint colors look correct rather than washed out.
For utility applications — storage, garages, service corridors — CRI 80 is entirely adequate and the price difference is better spent elsewhere.
Look Past CRI Ra for Critical Work
CRI Ra is an average across eight pastel test colours and does not include a saturated red sample. A strip can post a respectable Ra figure while rendering deep reds poorly, which shows up immediately on meat, wood tones, cosmetics and skin. Where red rendition matters, ask for the R9 value specifically — R9 > 50 is a reasonable floor and R9 > 90 is excellent. For the most demanding work, the newer TM-30 metrics (Rf for fidelity, Rg for gamut) describe colour performance far more completely than a single Ra number.
12V or 24V COB LED Strip?
Both voltages exist in COB, and the choice follows the same logic as SMD strips, with one COB-specific consideration.
12V COB LED strips suit short runs, cabinet lighting and installations connected to existing 12V DC systems — vehicles, boats, RVs and solar setups. For the same model, 12V versions usually have the shorter cut interval, because each series group contains fewer LEDs than the 24V equivalent — which is an advantage when you need to trim to a precise length.
24V COB LED strips are the better choice for anything longer than about 5 meters from a single feed point. At the same wattage, 24V draws roughly half the current of 12V. Because voltage drop scales with current (V = I × R), that halves the drop along the run; because heating loss scales with the square of current (P = I²R), it cuts copper heating to roughly a quarter.
The Voltage Drop Question
Voltage drop is the practical limit on run length. As current flows along the copper trace, resistance causes the voltage at the far end to sag below the voltage at the feed point — and LEDs dim as voltage falls. On a long run, the last meter can be visibly dimmer than the first.
Some COB strips are specifically engineered for extended runs with heavier copper weight in the PCB, allowing 10m or more from a single feed point without visible dimming at the far end. If your project involves a long continuous run — a perimeter cove, a corridor, a retail shelf line — look for this specification explicitly. It is not universal, and a standard strip will show visible falloff over the same distance.
Where the specification is not available, the practical rule is to add a power injection point every 5m on 12V and every 10m on 24V.
Cut Intervals: The Detail Most Buyers Miss
Every LED strip can only be cut at marked points, where the circuit completes a series group. Cut anywhere else and that segment goes dark.
On COB strips the cut interval depends on density, voltage and how the manufacturer has arranged the series groups. As an illustration, one 312 LEDs/m model cuts every 19.23mm at 12V and every 38.46mm at 24V; a 320 LEDs/m model cuts every 25mm at 12V and every 50mm at 24V. These are examples, not universal values — the cut interval is a per-SKU specification and must be read off the product page.
Why this matters: if you are lighting a 400mm display shelf and your strip cuts every 50mm, your options are 400mm exactly or 350mm — no middle ground. On a 19mm cut interval you have far more precision, which is often the deciding factor on projects with many short custom runs.
Before ordering, check the cut interval against the lengths you actually need. For projects with many short custom runs — display cases, sign channels, furniture recesses — a shorter cut interval saves material and avoids visible gaps at the ends of runs.
Where COB LED Strips Work Best
Cove and perimeter lighting. COB's wide beam angle washes ceilings and walls more evenly than SMD, and the dotless output means no visible reflection points on glossy ceiling surfaces.
Under-cabinet kitchen lighting. The continuous line eliminates the striped shadow pattern that SMD strips cast onto countertops. With a reflective backsplash, the difference is immediately visible.
Display cases and retail shelving. High CRI plus dotless output makes COB the standard choice for jewellery cases, museum vitrines and high-end retail merchandise lighting.
Stair and step lighting. Continuous illumination along the tread edge reads as a clean architectural line rather than a series of points.
Mirror and vanity lighting. High CRI matters for skin tones; the dotless output avoids the visible LED reflections that appear in the mirror with SMD strips.
Furniture and millwork detailing. Toe-kicks, shelf edges, headboard perimeters, reception desk details — anywhere the light line is part of the design intent rather than just illumination.
Signage and channel letters. The continuous output produces even fill across letter faces without the hotspotting that discrete LEDs can cause on shallow returns.
Installation Notes Specific to COB
Most COB installation practice matches SMD, with a few differences worth noting.
Cut only at marked points. COB cut marks can be less visually obvious than on SMD strips, where the gap between packages makes the cut zone clear. Look for the printed cut line and scissor icon on the PCB.
Aluminum channel is strongly recommended. COB strips at 8–11W/m generate real heat. An aluminum profile conducts it away from the board and extends the lifespan of both the LEDs and the phosphor layer. Channel mounting also protects the phosphor surface, which is more exposed than the encapsulated packages on an SMD strip.
A clear cover is usually sufficient. One of COB's advantages is that you don't need a frosted diffuser to hide dots — so use a clear or lightly frosted cover and keep the light output.
Handle the phosphor surface carefully. The continuous phosphor layer is more susceptible to scratching and contamination than the hard-encapsulated packages on SMD tape. Avoid dragging the lit surface across rough materials during installation.
Size the driver with headroom. Multiply W/m by total length, then add at least 20%. A 5m run of an 11W/m strip draws 55W, so specify a 70W or larger driver.
Dimming works normally. COB strips are constant-voltage and dim with a PWM dimmer rated for the correct voltage and total wattage. Never wire a low-voltage strip directly to a mains phase-cut dimmer — the dimmer belongs on the AC side of the driver, not between the driver and the strip. TRIAC dimming does work in this category, but only through a driver explicitly specified as TRIAC-dimmable; pair a standard non-dimmable driver with a wall TRIAC dimmer and you get flicker, buzzing or a damaged driver.
Frequently Asked Questions
Are COB LED strips brighter than SMD?
Not automatically — brightness depends on wattage and efficacy, not construction. What COB does deliver is more usable brightness in practice, because it doesn't need a frosted diffuser. An SMD strip behind a diffuser loses 20–30% of its output; a COB strip behind a clear cover keeps it. At the same rated lumens, the COB installation is typically brighter at the surface.
Do COB LED strips need a diffuser?
No. That's the point of the construction. A clear cover protects the strip without sacrificing output. Some installers still use a light frost for a softer edge, but it isn't required to hide dots.
Can COB LED strips be cut?
Yes, at the marked cut points. The interval is set by how the series groups are arranged and varies by SKU — commonly somewhere between 19mm and 50mm, with the 12V version of a given model usually cutting at shorter intervals than its 24V counterpart. Check the stated cut interval on the product page before ordering if you need precise custom lengths.
Are COB LED strips waterproof?
Depends on the model. COB strips are available in IP20 (dry indoor), IP65 (splash-resistant) and IP67 (fully encapsulated) versions. Check the IP rating on the product page and match it to the environment. For outdoor and wet-location projects, see Outdoor & Waterproof LED Strip Lights.
What's the difference between COB and FCOB?
FCOB stands for Flexible Chip on Board — it's the same technology, with "flexible" emphasizing the bendable PCB. In practice the terms are used interchangeably in the LED strip market. Both describe dies bonded directly to a flexible board under a continuous phosphor layer.
How long can a COB LED strip run from one power supply?
It depends on wattage per meter, PCB copper weight and voltage. Standard strips manage roughly 5m at 12V and 10m at 24V before visible dimming. Some COB strips are engineered specifically for 10m runs without voltage drop — check whether the product states this explicitly, since it's a design feature rather than a given.
Does COB last longer than SMD?
Both use the same underlying LED die technology and rated lifespans are comparable. COB's advantage is thermal: heat spread across the full board rather than concentrated at individual packages generally means lower junction temperatures and better lumen maintenance over time, particularly in enclosed channels. Proper heatsinking matters more than construction type either way.
Choosing a COB Strip: Quick Checklist
- Density — 312–320 LEDs/m for general use; 384–480 LEDs/m for display cases and close-viewing applications
- CCT — 2700K–3000K for residential warmth; 3500K–4000K for neutral and commercial; 6000K for task and inspection
- CRI — 90+ for retail, food, art, beauty and residential living spaces; ask for R9 or TM-30 figures where red rendition matters
- Voltage — 12V for short runs and vehicle systems; 24V for anything over 5m and all commercial work
- Cut interval — read the per-SKU figure and check it against the specific lengths your project needs
- Run length — confirm the maximum specified run, and whether the strip is engineered for extended runs
- IP rating — IP20 indoors; IP65 or IP67 for damp and wet locations
- Wattage — calculate total load and size the driver with 20% headroom
Browse the full range at COB LED Strip Lights.
Related reading: Single Color LED Strip Lights · Tunable White LED Strip Lights · Outdoor & Waterproof LED Strip Lights · Commercial & Specialty LED Strip Lights
