Whether you're buying them online or in the store, there are a lot of options for LED recessed lights. This category covers the 6 specifications you should be familiar with when deciding which lights to use.
Modern LED lights range in size between 2-inches and 6-inches. Most homes use 4-inch and 6-inch lights.
I recommend using the following approach to choosing the size of recessed lights for a room:
#1: Start with Consistency - If you already have recessed lighting in some parts of the house, consider whether you want to match their size to keep everything consistent. If you don't, then move on to #2.
#2: Visual preference - What size looks good to you? Consider the scale of the room. It's been common practice to use large lights for general lighting and small lights for task and accent lighting, however it is becoming increasingly popular to use the smaller lights throughout.
#3: Budget - Using 3-inch or 4-inch recessed lights may cost a little more overall because you'll likely need a few more lights to fill the same size space verses using 5-inch or 6-inch lights.
One last note about recessed light sizes. When a light says it's a "4-inch" or "6-inch", that is the measurement across the inside of the housing (diameter) with the trim removed.
If your ceiling is flat, use fixed (aka straight or non-adjustable) recessed lights for general and task lighting. Use adjustable lights on flat ceilings when you want to direct the light towards the walls for accent lighting and wall washing.
If your ceiling is sloped, you'll need to choose between fixed or adjustable recessed lights. The reason to consider using adjustable lights is they can be directed downward rather than following the angle of the ceiling like fixed lights will. Aiming them downward reduces glare and is very beneficial when the seating in a room is facing the slope of the ceiling.
3. Color Temperature
Not to be confused with brightness, correlated color temperature (CCT) is the actual color appearance of the white light, measured in Kelvins (K). The three most common color temperatures are warm white (2700K), soft white (3000K), and daylight (4000K or 5000K).
When choosing a color temperature, start with what is currently being used in the home. If there is lighting that you already find comfortable, I suggest matching it as close as possible for consistency. If not, I recommend 2700K or 3000K color temperature for inside the home.
The brightness of LED recessed lights is given in lumens, not watts like incandescent lamps of the past. Don't make the mistake of comparing watts between LED lights to compare brightness. Some LEDs are more efficient than others and therefore use less watts to produce the same or more lumens.
For general lighting, I recommend using lights that produce at least 600 lumens for standard height ceilings, and at least 900 lumens for tall ceilings.
5. Quality of Light
Color rendering index (CRI) is the measurement of a light's ability to display colors accurately in comparison to an ideal or natural light source. Using LEDs with a high CRI is important because it means that when the light illuminates a room or an object, the colors will appear as they were intended.
The LED lights you choose should have a CRI of 90 or higher.
6. Beam Angle
A light's beam angle is where it's concentration is 50% or greater. Most LED recessed lights (aka "Retrofit" LEDs) have a very wide beam angle, especially the style where the lens is not very recessed into the fixture. While this is great for spreading light, just remember that too wide of angle can cause excessive glare when looking across a ceiling.