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LED Strip Lighting Guide: Lumens, Wattage & Profile Selection
How many lumens does your room actually need, how long a strip can you run before it dims, what power supply to buy, and which profile/diffuser to pick — all in one place, with a calculator so you don't have to do the maths yourself.
LED strip brightness calculator
Enter your room size and pick a use case — this estimates how much strip length, wattage, and power-supply size you need.
Room area100 sq ft
Approx. lumens needed1,500 lm
LED strip length required5.5 ft (1.7 m)
Total strip load20 W
Recommended power supply≥ 36 W 12V
Power feed points needed1
This is a planning estimate using typical LED strip output bands (not a photometric lighting-design calculation). Lumens per watt/meter vary by brand and LED bin — confirm exact figures against your chosen product's datasheet before buying. Power supply sizing includes a standard 20% headroom for long-term reliability.
Brightness bands by application
LED strip output is usually sold in lumens per foot (lm/ft) rather than raw lumens — here's what each band is typically used for.
| Application | Output | Approx. power |
|---|---|---|
| Accent / mood / cove / toe-kick / TV backlight | 100 – 200 lm/ft | ~2 – 2.5 W/ft |
| Under-cabinet ambient | 200 – 250 lm/ft | ~2.5 – 3.3 W/ft |
| Under-cabinet task / general room fill | 250 – 350 lm/ft | ~3.3 – 4.5 W/ft |
| Indirect / cove lighting (brighter) | 150 – 300 lm/ft | ~2 – 4 W/ft |
| Task lighting, signage, retail displays | 300 – 500+ lm/ft | ~4.5 – 6.5 W/ft |
Room-wise lumen targets
Multiply your room's floor area (sq ft) by these figures for a rough total-lumens target — the calculator above does this for you.
| Room / space | Target output |
|---|---|
| Corridors / passages | 5 – 15 lm/ft² |
| Living rooms (ambient) | 10 – 20 lm/ft² |
| Kitchens / worktops (task) | 30 – 50 lm/ft² |
| Home offices | 30 – 50 lm/ft² |
LED chip type & density comparison
Typical specs by chip/density — actual output and watts vary by brand and LED bin, so always check the datasheet of the specific strip you buy.
| Chip / density | Lumens/m | Watts/m | Notes |
|---|---|---|---|
| SMD2835, 60 LED/m | ~900 – 1,000 lm/m | ~9.6 – 12 W/m | Best lm/W efficiency; most common general-purpose density |
| SMD2835, 120 LED/m | ~1,800 – 2,000 lm/m | ~14.4 – 19.2 W/m | High-output accent/task strips; runs warmer, shorter max run |
| SMD5050, 30 LED/m | ~450 – 500 lm/m | ~7.2 W/m | Lower density, larger individual chip; common in RGB strips |
| SMD5050, 60 LED/m | ~900 – 1,000 lm/m | ~14.4 W/m | Less efficient per watt than 2835 at the same output |
| COB (continuous) | ~1,000 – 2,000 lm/m | ~10 – 14 W/m | Dot-free even light line, typically CRI 90+, best for linear coves |
Voltage drop & maximum run length
Every metre of LED strip has tiny copper trace resistance — over distance that drops voltage and dims/colour-shifts the far end. Keep single feeds within these limits, or power from both ends / add a second feed point for longer runs.
| Voltage | Max run per feed | Why |
|---|---|---|
| 12V DC | ~5 m (16 ft) per single feed point | Most common for small domestic runs; feed from both ends to double effective length |
| 24V DC | ~10 m (33 ft) per single feed point | Preferred for longer runs — half the current draw of 12V for the same wattage, so less voltage drop |
A common tolerance is 3% voltage drop for colour-critical work and up to 5% for general accent lighting. Thicker supply wire and shorter feed distance both reduce drop.
Wire gauge & voltage drop calculator
Check whether your planned supply wire can carry the run without excessive dimming — enter your load, voltage, wire run and the copper wire size you're using.
Current draw5.00 A
Voltage drop0.57 V (4.8%)
Voltage at far end11.43 V
3–5% drop — acceptable for general accent lighting, but you may notice slight dimming or warmth shift at the far end.
Formula: Vdrop = 2 × length × current × resistance/m (copper). Figures are a planning estimate at room temperature — real-world drop can be slightly higher under load.
Power supply sizing
Rule of thumb: power supply watts = total strip watts × 1.2 (20% headroom), rounded up to the next standard driver size. Running a driver continuously at 100% load shortens its lifespan — the margin keeps it cooler and more reliable long-term.
Running cost calculator
Estimate what your LED strip (or any other load) actually costs to run, based on your electricity rate.
Daily running cost₹1.92
Monthly running cost₹58
Yearly running cost₹701
Default rate (₹8/unit) is a typical Indian residential average — edit it to match your own electricity bill slab for an accurate figure. 1 unit = 1 kWh.
Colour temperature & CRI
Colour temperature (Kelvin) is the warmth/coolness of the light. CRI (0–100) is a separate measure of how accurately it renders colours — a light can be any colour temperature and still have poor or excellent CRI. For kitchens, wardrobes and anywhere colour accuracy matters, look for CRI 90+.
| Kelvin | Name | Typical use |
|---|---|---|
| 2700K | Warm white | Bedrooms, living rooms, dining — cosy, relaxed |
| 3000K | Soft white | Most versatile for home interiors — kitchens, hallways, hospitality |
| 4000K | Neutral white | Offices, kitchens (task), retail — balanced visibility |
| 5000K | Daylight | Workshops, warehouses, inspection/task areas |
| 6500K | Cool daylight | Factories, labs — maximum alertness/contrast |
IP rating — which do you need?
| Rating | Protection | Where to use it |
|---|---|---|
| IP20 | No water protection | Indoor only — bedrooms, living rooms, false ceilings |
| IP44 – IP65 | Splash / low-pressure jet resistant | Bathrooms (outside direct spray), covered outdoor areas, kitchens |
| IP67 | Temporary submersion (1 m, 30 min) | Permanent outdoor, gardens, near pools (not submerged) |
| IP68 | Continuous submersion | Underwater / fully submerged installations |
Choosing an aluminium profile/channel
A bare LED strip stuck directly to a surface looks fine until you see individual LED dots reflected on a glossy surface, or the heat shortens its life. An aluminium profile with a diffuser fixes both — spreads heat and evens out the light line.
Surface-mount channel
U-shaped aluminium channel screwed or stuck onto a wall, ceiling, or underside of a cabinet. Easiest to install, good heat dissipation, visible as a raised strip.
Recessed / flush channel
Set into a groove in a wall, ceiling, or furniture panel for a seamless, trim-free look. Needs the groove planned before civil/carpentry work.
Corner channel
V-shaped profile for 90° edges — cabinet corners, wall-ceiling junctions — angles light toward a surface instead of straight down.
Diffuser cover
Clear (85–95% transmittance, brightest, visible dots), semi-clear (70–80%, balanced), or opal/milky (30–40%, fully even line, dimmer) — pick opal for a clean light line, clear when maximum output matters.
LED strips in stock
LED Strip Light 2835 12V — 5 Meter Roll
60–240 LED/m density options, 2700K–6500K + RGB variants, IP20 (indoor) or IP65 (wet-area), IR remote dimmable.
Outdoor Wall Washer LED Strip 24W — IP65
48 LED/m, 24V input, 2700K–6500K/RGB options, IP65 waterproof — building facades and wall-grazing installations.
Frequently asked questions
How many lumens do I need for my room?
As a rough planning figure: living rooms need about 10–20 lumens per sq ft, kitchens and home offices need about 30–50 lumens per sq ft (task lighting), and corridors need about 5–15 lumens per sq ft. Multiply your room area by the relevant figure to get total lumens, then use the calculator above to convert that into strip length.
Should I choose a 12V or 24V LED strip?
12V is fine for short runs (up to ~5 m per feed point) like under-cabinet lighting. 24V halves the current for the same wattage, so it suffers less voltage drop and can run up to ~10 m per feed point — better for coves, long corridors, or whole-room runs.
Why does my LED strip get dimmer or change colour toward the far end?
That is voltage drop — resistance in the copper traces reduces voltage as current travels down the strip. It gets worse with longer runs, higher current, and thinner copper. Fix it by powering from both ends, splitting the run into shorter parallel feeds, or switching to 24V.
How do I size the power supply (driver) for an LED strip?
Calculate total wattage (strip length × watts per metre/foot), then add about 20% headroom and round up to the next standard driver size. Running a power supply continuously at 100% load shortens its life — the 20% margin keeps it running cooler and more reliably.
What CRI do I need?
CRI (0–100) measures how accurately a light source renders colours — it is independent of colour temperature (warm/cool). Below 80 CRI, colours look flat or off; 80+ is fine for general use; 90+ is recommended for kitchens, wardrobes, makeup areas, and anywhere colour accuracy matters.
What colour temperature should I pick — 2700K, 3000K, 4000K or 6500K?
2700K–3000K (warm/soft white) suits bedrooms, living rooms and dining areas for a relaxed feel. 4000K (neutral white) suits kitchens, offices and task areas. 5000K–6500K (daylight/cool) suits workshops, factories and spaces where alertness and contrast matter more than cosiness.
What IP rating do I need for a bathroom or outdoor install?
IP20 is indoor-only with no water protection. For bathrooms outside direct spray or covered outdoor areas, use IP44–IP65. For permanent outdoor or garden use, choose IP67. Only go IP68 if the strip will actually be submerged.
Surface, recessed, or corner aluminium profile — which one?
Surface-mount channels are the easiest retrofit (screw/stick on top of a surface). Recessed channels give a flush, trim-free look but need the groove planned in before civil or carpentry work. Corner channels angle the light at 90° edges like cabinet corners or wall-ceiling junctions.
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