The Lighting Facts panel was introduced because wattage stopped meaning brightness. It succeeded at that, and then kept growing until a modern carton carries nine or ten numbers, most shoppers read one of them, and it is often the wrong one. Here is the whole panel, in order of how much it should influence your choice.
Lumens: the only real brightness number
A lumen is a unit of luminous flux — total visible light emitted in all directions, weighted for the sensitivity of the human eye. It is the number that replaced wattage, and it is the first thing to look at.
The useful conversions, for a standard A-shape bulb:
| Old incandescent | Lumens | LED watts | Typical use |
|---|---|---|---|
| 25 W | ~250 lm | 3 W | Decorative, accent, night light |
| 40 W | ~450 lm | 5 W | Bedside, small table lamp |
| 60 W | ~800 lm | 9–10 W | General room lighting |
| 75 W | ~1,100 lm | 13–14 W | Kitchen, larger living room |
| 100 W | ~1,600 lm | 16–18 W | Workshop, garage, task |
One warning about lumens: the figure on the box is lamp lumens, measured in an integrating sphere with nothing around the bulb. What reaches your table is delivered lumens, after the fixture has absorbed some and the shade has absorbed more. A fabric drum shade can swallow 40%. When a lamp seems dimmer than the box promised, the fixture is usually the reason.
A rule of thumb for rooms
Aim for roughly 20 lumens per square foot of general lighting in a living room, 30–40 in a kitchen, 50–75 over a work surface. A 12 × 14 ft living room therefore wants about 3,400 lumens in total — which is four 800-lumen lamps, not one heroic bulb in the ceiling.
Kelvin: the colour of the white
Correlated colour temperature describes where the white sits between yellow and blue. It is measured in kelvin, and the scale runs backwards from how people describe it: low numbers are “warm” (orange), high numbers are “cool” (blue).
| Kelvin | Appearance | Comparable to | Best for |
|---|---|---|---|
| 2200 K | Deep amber | Candlelight | Decorative filament, late-evening lamps |
| 2700 K | Warm white | Classic incandescent | Living rooms, bedrooms, dining |
| 3000 K | Soft white | Halogen | Kitchens, bathrooms, hospitality |
| 4000 K | Neutral white | Morning daylight | Offices, utility rooms, garages |
| 5000 K | Cool white | Overcast noon | Workshops, inspection, task lighting |
| 6500 K | Daylight | Clear north sky | Colour matching, clinical work |
Two practical points. First, mixing colour temperatures within a single sightline reads as a fault rather than a design choice — the eye adapts to one white and judges everything else against it. Second, warmer light in the evening interferes less with melatonin, which is the honest, non-mystical version of the “blue light” argument. Both are covered in more depth in the room-by-room guide.
CRI and R9: colour rendering
Colour rendering index compares how objects look under the lamp against how they look under a reference source of the same colour temperature. It runs to 100 and is computed from how faithfully the lamp renders a set of standard test colours.
The general CRI figure — properly, Ra — averages the first eight test colours, all of them muted pastels. That averaging hides a specific, visible failure: R9, the deep red sample, is not included in Ra at all. An LED can score CRI 82 and still render red poorly, because the phosphor mix is thin in the deep-red region.
- CRI 80–84. Acceptable for corridors, garages, storage, exterior. Colours are recognisable; nothing looks good.
- CRI 85–89. Fine for general residential use.
- CRI 90+ with R9 > 50. Specify this for kitchens, bathrooms, dressing areas, retail display, food service and anywhere skin tone or fabric colour matters.
- CRI 95+ with R9 > 90. Colour-critical work: print, paint matching, cosmetics, medical.
If a manufacturer publishes CRI but not R9, assume R9 is low. Nobody hides a good number.
Beam angle and distribution
Beam angle describes the cone within which the lamp emits at least half its peak intensity. It is the difference between filling a room and lighting a painting.
- 15–24° (narrow spot). Accent lighting, artwork, retail feature displays.
- 25–40° (spot). Kitchen work surfaces, general track lighting, the standard GU10 replacement.
- 40–60° (flood). General downlighting on 8 ft ceilings.
- 120°+ (wide). Downlights on high ceilings, wall washing.
- 200–300° (omnidirectional). A-shape and candle lamps in shades and open fittings.
A common and expensive mistake: fitting narrow spots in a kitchen ceiling produces bright discs on the floor and shadowed work surfaces. The correct answer is usually a wider beam and more of them, or task lighting under the cabinets.
The other half of distribution is whether the lamp emits backwards. Many early LED “bulbs” emitted only forwards, which was invisible in a downlight and glaringly obvious in a table lamp with a translucent shade — the top half of the shade stayed dark. Check for a stated omnidirectional rating if the fitting shows the lamp.
Rated life, energy use and estimated cost
Three numbers usually printed together, and all three are assumptions dressed as facts.
Rated life is the L70 hours figure discussed in the technology comparison. Divide it by your own daily burn hours, not by three.
Energy use in watts is straightforward and is the one number on the panel that is simply true.
Estimated yearly cost is computed at a fixed assumed tariff — in the US, 11 cents per kilowatt-hour, a figure set years ago and now below the national average almost everywhere. If your tariff is 22 cents, double every cost figure on the carton. Our calculator uses your real number.
Working out the cost yourself
Annual cost = watts × hours per day × 365 ÷ 1000 × your rate per kWh.
A 10 W lamp, 4 hours a day, at 18¢/kWh: 10 × 4 × 365 ÷ 1000 × 0.18 = $2.63 a year.
Base type, shape code and physical fit
The most common reason a bulb goes back to the shop is that it does not fit — either electrically or mechanically.
Base codes start with a letter for the type and a number for the size in millimetres. E26 is the standard North American medium screw; E27 is its European equivalent and physically interchangeable, though the voltage is not. E12 is the candelabra base. GU10 is a twist-lock two-pin spot base; GU5.3 is the push-fit low-voltage equivalent. B22 is the UK bayonet.
Shape codes describe the envelope: A19 is the classic pear at 19 eighths of an inch diameter, B11 is the candle, G25 is the round vanity globe, BR30 and PAR38 are reflector shapes, ST64 is the vintage tube.
Then check the physical envelope. LED lamps are often slightly longer than the incandescent they replace, because the driver electronics and heat sink sit between the base and the light-emitting part. In a shallow enclosed fitting or a tight recessed can, that extra 8 mm is the difference between fitting and not.
Enclosure, damp and dimming ratings
These live in the small print and they are the ones that decide whether the lamp reaches its rated life.
Enclosure rating. An LED lamp in a sealed globe runs hotter than the same lamp in open air, and heat is what kills LED drivers. A lamp not rated for enclosed fixtures may lose more than half its rated life in one. Rated lamps have a larger heat sink and components specified for the higher temperature. Every uBRITE A19 and candle lamp is enclosure-rated; the clear filament lamps are not, because the aesthetic requires a slim base.
Damp and wet rating. Damp-rated means protected from condensation and humidity — bathrooms, covered porches. Wet-rated means direct water contact is acceptable — exposed exterior. Using a dry-rated lamp in a bathroom is a slow failure; using it outside is a fast one.
Dimming rating. “Dimmable” on the carton means the lamp can dim, not that it will dim on your circuit. Manufacturers publish compatibility lists naming tested dimmer models. If you care about the result, read the list before you buy forty lamps.
A one-minute buying checklist
In the aisle, in order:
- Lumens — from the room calculation, not from the old bulb’s wattage.
- Kelvin — matching everything else in the same sightline.
- CRI — 90+ if anyone will look closely at anything.
- Base and shape code — read off the old lamp.
- Beam angle — only for directional lamps.
- Enclosure and damp rating — if the fitting is sealed or wet.
- Dimmable — and on the dimmer compatibility list if the circuit is dimmed.
- Warranty — and whether it needs registering. Ours does, and it takes two minutes.
Wattage does not appear on that list except as an input to the running cost. That is the whole point of the Lighting Facts panel.
Common questions
Nothing enforceable. It is a marketing convention meaning roughly 800 lumens, and different manufacturers apply it to lamps ranging from 720 to 850 lumens. Read the lumen figure instead — it is measured and regulated.
Yes, room by room. Not within one sightline. A 4000 K kitchen next to a 2700 K dining room is fine if you cannot see both at once; two different whites in the same ceiling looks like a fault.
Slightly. Broadening the spectrum to render colour well costs a few percent of efficacy, so a CRI 95 lamp might give 95 lm/W where its CRI 80 sibling gives 105. On a 10 W lamp that is under a watt, and worth it wherever colour matters.
