Does your home or shop still feel dim even with 20 lights? Can’t look up because spotlights glare too harshly? 90% of lighting missteps come down to choosing the wrong fixture type and miscalculating quantities.
In interior lighting design, downlights and spotlights are workhorse fixtures—picking the right ones and getting the count right directly impacts a space’s lighting effect and overall ambiance. Let’s break down how to select these fixtures and calculate the numbers you need.
What’s the difference between downlights and spotlights?
Downlights, available as both surface-mounted and recessed fixtures, cast uniform, soft light—falling into the category of flood lighting. Their primary role is to provide ambient illumination, brightening entire spaces evenly. This makes them perfect for living rooms, bedrooms, dining areas, and other spaces where large-scale, consistent lighting is needed.
Spotlights, also offered in surface-mounted and recessed designs, emit focused, directional light, serving as key accent fixtures. Their core function is to concentrate light precisely, enhancing the shape and texture of specific objects while creating striking light-and-shadow contrasts. This targeted approach makes them versatile across settings:
- Residential spaces: Highlighting artwork, collectibles, or plants on feature walls, bookshelves, or entryway displays.
- Commercial & cultural venues: Drawing attention to retail window displays, museum exhibits, or gallery pieces.
Helpful Lighting Terms Knowledge
| Terms | Definition and application | Differences between downlight and spotlight |
| Lumen | Total required light output for a space | Downlights excel at ambient lighting; spotlights specialize in accent lighting. |
| Beam Angle | Downlight (60°-120°) vs spotlight (15°-45°) | Narrow-angle for accent lighting, wide-angle for uniform lighting |
| CCT | 2700k warm white to 6500k cold white | Recommended to keep the color temperature consistent within the same space. |
| CRI | ≥90 restore true color | Spotlights require a higher CRI than downlights. |
Determine the number of fixtures based on per-square-meter requirements
Step 1: Determine the illuminance requirements for a space
|
Space |
Recommended Illuminance (lux) |
Converted Lumen (lm/㎡) |
|
Bedroom/Corridor |
100-150 |
300-450 |
|
Living Room/Kitchen |
150-300 |
450-900 |
|
Study/Bathroom |
300-500 |
900-1500 |
|
Art Gallery |
500+ |
1500+ |
Step 2: Calculate the total lumen requirement
Step 3: Allocate quantities for downlights and spotlights
Step 4: How to choose downlight vs spotlight?
Step 5: Are there other factors to consider?
-
Ceiling height: The taller the space, the more light is lost as it travels downward. This means you may need to either add more fixtures or opt for higher-wattage ones. As a general rule, for every 1-meter increase in ceiling height, you can adjust by either upping the fixture power by 1-2W or adding 1-2 extra fixtures to your original plan.
-
Wall and floor colors: Light-colored walls and floors reflect light more effectively, which boosts a space’s overall brightness. In such cases, you can safely reduce the number of fixtures. Darker surfaces, on the other hand, absorb more light—so you’ll need additional fixtures to ensure adequate illumination.
- Usage scenarios: Activities that demand brighter light, like reading or office work, require higher illuminance per square meter, which means more fixtures. For more relaxed settings focused on ambiance—such as casual lounging—you can lower the illuminance and reduce the number of fixtures.
