Quick answer: COB means chip on board: LED chips are mounted directly on the board and covered with an encapsulant, according to Wikipedia's chip-on-board overview. Consider a COB strip for a linear lighting project, then choose the specific model by light output, power demand and cut spacing.
This guide compares actual strip listings and shows how to calculate a cut length and power requirement. COB describes construction; it does not, by itself, establish brightness, efficiency or suitability for your installation.
What makes a strip COB?
The defining feature is the way the chips are assembled. According to Wikipedia, chip-on-board assembly covers the chip and its connections with an encapsulant; the substrate may also include heat-dissipating layers for power-handling applications such as LED lighting.
For white light, the same Wikipedia overview describes a silicone layer containing yellow Ce:YAG phosphor that converts the LEDs' blue light into white light. That explains the role of the coating without assuming every coloured COB product has the same construction.
Keep the construction question separate from the buying question. A useful shortlist needs a stated output, a colour specification and electrical ratings, not just the letters COB on the package.
Which COB strip should you choose?
Compare the exact models: the listings below have different outputs and cut intervals despite sharing a supply voltage. These are product examples, not universal COB specifications; the RGB entry is not a like-for-like white-light comparison.
| Model and source | Supply | Power per metre | Listed output per metre | Cut interval |
|---|---|---|---|---|
| According to Cutter, AGRCOB-24-840-20-RGB | 24 V DC | 12 W | Maximum 680 lm | 50 mm |
| Cutter, AGRCOB-24-512-20 | 24 V DC | 14 W | Maximum 1,680 lm | 62.5 mm |
| ADM, CB-PRO-24V-5M-10MM-40K | 24 V DC | 19.2 W | 2,496 lm | 27.7 mm |
Lumens describe light output; watts describe electrical power. Choose the output you need, then calculate the load rather than treating a higher wattage as the goal.
Colour specifications also distinguish the products. Cutter's white strip lists a minimum CRI of 90, while ADM's listed model specifies 4000 K. CRI describes colour rendering; kelvin describes colour temperature. Neither number substitutes for the other.
Is COB better than SMD?
A higher chip count is a measurable distinction in these examples, but it does not prove that every COB strip is brighter or more efficient. According to Cutter's RGB listing and related products, its RGB COB strip has 840 LEDs per metre. Cutter's white COB model has 512 LEDs per metre.
Use those counts as a contrast between particular products. They do not establish a fixed density for either construction type, nor do they prove that a finished installation will have no visible bright spots.
For a cabinet edge, shelf or decorative line, compare the appearance of your intended strip and housing together. Our LED strip diffuser guide covers the covering choice. For task lighting, start with listed lumens and colour specifications rather than chip count alone. The facts here do not support a blanket COB advantage in lifespan, price or heat generation.
Can you cut COB strips to fit?
Yes, but use the model's marked cut points. The intervals differ: Cutter's white strip specifies 62.5 mm, whereas ADM's model specifies 27.7 mm. A strip that can be cut is not a strip that can be cut anywhere.
Worked cut-length example — assumed inputs
Assume a usable recess length of 980 mm and a strip with 62.5 mm cut spacing, matching the Cutter listing. Assume no additional end clearance is required for this geometry example.
- Complete intervals = floor(available length ÷ cut interval).
- 980 ÷ 62.5 = 15.68; rounding down gives 15 complete intervals.
- Strip length = 15 × 62.5 = 937.5 mm.
- Unfilled length = 980 − 937.5 = 42.5 mm.
- The next interval would give 16 × 62.5 = 1,000 mm, exceeding the recess by 1,000 − 980 = 20 mm.
That result is a fitting decision, not an electrical limit. Allow for the actual end fittings before choosing the available length, then measure to the marked cut points with power disconnected.
How much power does a COB strip need?
Multiply length by the model's watts per metre, then divide by its supply voltage to calculate current. The LED strip calculator uses these formulas and adds its planning figure of 20% power headroom, rounding the suggested supply wattage up to the next 10 W increment. Its COB presets are estimates, so use the product rating for a model-specific calculation.
Worked power example — assumed inputs
Assume 5 m of strip rated 14 W/m at 24 V DC, using the ratings of Cutter's white COB model. Apply the calculator's planning method:
- Strip power = length × power per metre = 5 × 14 = 70 W.
- Strip current = power ÷ voltage = 70 ÷ 24 = 2.9167 A, approximately 2.92 A.
- Headroom multiplier = 1 + 20 ÷ 100 = 1.2.
- Power with headroom = 70 × 1.2 = 84 W.
- Rounded supply planning figure = ceil(84 ÷ 10) × 10 = ceil(8.4) × 10 = 9 × 10 = 90 W.
The result is a 24 V DC supply rated at least 90 W under this planning method. It covers the assumed strip load; it does not establish controller capacity, cable sizing or an allowable continuous run length. Add any other loads before repeating the calculation. Use a qualified electrician for mains-voltage connections.
What should you check before mounting it?
Check physical fit and location suitability as well as power. Both Cutter's RGB listing and its white-strip listing specify a board 10 mm wide and 1.4 mm high, an operating range of −25 to 55 °C, and IP20 for dry indoor use. These are model ratings, not dimensions or limits for all COB tape.
- Match the housing to the board and end fittings; our LED strip channel guide covers that part of the layout.
- Match the location to the strip's environmental rating rather than assuming an encapsulated chip makes the whole strip weatherproof.
- Plan heat dissipation for the selected power per metre. According to the DOE thermal-management fact sheet, excess heat can cause reversible colour shift and reduced light output, and accelerate lumen depreciation over time.
The practical inference is to consider the mounting arrangement's heat path when choosing a strip. The COB label alone does not establish how cool the finished installation will run.
FAQ
Are all COB LED strips 24 V?
No universal voltage follows from the COB name. The Cutter white model and ADM model here are both rated 24 V DC; those examples do not establish a rule for every COB strip.
Are COB strips always dotless?
Do not treat that description as a guarantee for a finished installation. According to Cutter, its RGB example has 840 LEDs per metre, but chip density alone does not verify the appearance of your chosen housing and viewing position.
Can a COB strip produce RGB colours?
Yes. According to Cutter's RGB product listing, that model is an RGB COB strip rated 12 W/m at 24 V DC.
Is there a maximum wattage for all COB tape?
The examples do not establish a universal maximum. ADM's model is rated 19.2 W/m; calculate from the selected product rather than applying a supposed COB-wide ceiling.
Can I use these strips outdoors?
The Cutter white strip is an IP20 dry-indoor example. It is not a suitable basis for specifying an exposed outdoor installation; select a product rated for the actual location.
Jack Shi
Founder & editor, LEDaskJack Shi builds and writes LEDask, an independent LED-lighting tools project operated by clooms. He designs the calculators, checks their formulas and reference values against published engineering data, and writes the guides across the site.
