Bulbs, Color Temperature and Brightness

Buying bulbs is genuinely simple once you know to turn the box over. The large friendly "60W equivalent" on the front is a translation for people who have not switched from incandescent yet, and manufacturers apply it loosely - two bulbs both labeled 60W equivalent can differ by 150 lumens.

The useful information is in the Lighting Facts panel on the back, and it is three numbers.

R9 deserves a note. CRI is an average across a set of reference colors, and in the most common calculation the deep-red sample is not among them - so a bulb can post a respectable CRI while rendering reds poorly. Since skin, wood, brick and cooked food all depend heavily on red content, that omission is why a room can look slightly wrong under a light that measures fine on paper. Almost no mainstream brand publishes R9, and the ones that do are telling you something.

Before buying a lamp, read the lumen figure on the bulbs already in the room. This is where a surprising number of dark rooms are actually solved.

Two checks before you do it. Look for the maximum wattage marked on the fixture, comparing against the LED's real draw rather than its equivalence. And avoid putting a high-output LED into a fully enclosed fitting, where trapped heat shortens its life considerably.

"Soft white," "warm white," "bright white" and "daylight" are marketing conventions, not standards. Different retailers apply them to different kelvin values, so two boxes carrying the same words can genuinely be different colors - which is how a room ends up with three whites in it after a year of buying bulbs one pack at a time.

The fix is to ignore the phrase and read the kelvin figure, and to buy in multipacks of one specification rather than replacing bulbs individually. The full mapping is in warm white vs soft white vs daylight, and the chart of what each value looks like in a room is in the color temperature guide. If you still cannot choose, the best color-selectable LED bulbs carry several settings on a switch, so one pack decides it in your own room.

Two of the most common bulb complaints are not bulb problems, and this section exists so you do not spend money solving the wrong thing.

Flicker on a dimmer is usually a dimmer mismatch. Old leading-edge dimmers were built for incandescent filaments and handle low-load LED drivers poorly, and many need a minimum wattage that three modern bulbs do not reach. You can work through several brands of bulb and get the same result - diagnose it first in why dimmable LED bulbs flicker.

Light that feels too harsh is usually glare rather than quantity. An LED produces its output from a much smaller area than an old frosted incandescent, so it reads as intense even when the room is not brighter. Shading or aiming it fixes that; reducing the output makes a dark room darker. When LED lights are too bright separates the two.

Most of this hub is about choosing light. These five are about choosing a bulb for a socket with its own rules.

• BR30 bulbs for recessed cans - the flood bulb a ceiling of cans was built around.
• Appliance bulbs - the oven, the fridge and the microwave each want something different.
• G25 globe bulbs for a vanity - where diffusion and CRI matter more than output.
• Garage door opener bulbs - vibration, and the interference that shortens remote range.
• GU10 bulbs for track heads - the twist-lock spot, and the 12V lookalike that will not fit.

Five head-to-head pages for the choices that come up at the shelf.

• 4000K vs 5000K - the last neutral white against a working light.
• A19 vs BR30 - same socket, and only one of them suits a recessed can.
• Clear vs frosted bulbs - glare against a few percent of output.
• Dim to warm vs standard dimming - what an incandescent did on the way down.
• Best flicker-free LED bulbs - what the makers claim, and the phone test.

The brightest LED bulbs you can actually fit - the ladder from 800 lumens to 4,000, and the two limits that decide how far up it your fixture lets you go.

The best LED tube lights - replacing a fluorescent tube, and the ballast question that decides which type you need.

The best rechargeable emergency bulbs - bulbs with a battery inside, and the switch rule that decides whether they work.