How many downlights do I need?

The recessed downlight, or can light, is popular for home and office lighting. And for good reason: downlights are energy efficient, stylish, and versatile. But before you install any old number of downlights, it’s important to understand how to calculate the number of downlights you’ll need for your space.

Downlights – how to calculate how many you need

When you sit down with pen and paper and try to work out “how many LED downlights do I need?” (we’ve used LED bulbs purely as an example, as these are becoming the most popular downlight bulb type), remember that there are many factors in play, before making any big decisions. There are a few things that go into calculating the number of downlights you need:

  • The size of the room or area you’re lighting
  • The height of the ceilings
  • The type of downlight you’re using (halogen or LED)
  • The amount of lumen (light) each bulb can emit.
  • Will the room require even lighting or areas of more intense light?

Now follow these steps to calculate the number of required downlights to evenly light a room.

1) Calculate the area

Measure the room, and multiply the length by the width, using feet for this calculation. For example, 13ft x 10ft = 130 square feet.

2) Estimate the required wattage.

If you are using LED downlights, multiple the above number by 0.3.

For example: 130 x 0.3 = 39 Watts

If you are using halogen downlights, multiple the above number by 1.5

For example: 130 x 1.5 = 195 Watts.

3) Look up the wattage on the bulb you will use.

For example, a 10 Watt LED bulb is equivalent to a 42 Watt halogen bulb.

4) Calculate how many downlights you will need.

Divide the answer from step 2 by the wattage value in step 3.

So, for example, if you’ve opted to go with LEDs at 10 Watts each, your calculation would be 39 / 10 = 3.9 bulbs. We’d round up to 4.

If you stick with halogen, your calculation would be 195 / 42 = 4.6 bulbs. We’d round that up to 5.

how many downlights

How to place downlights

This is only a rough guide to how many lights you want to put into your room. For example, symmetry might matter to your room design, in which case you might wish to add a halogen bulb to the 5 we calculated above to allow you to run three on each side of the room or stick with five in a cross pattern.

General wisdom dictates that downlights are placed between 1m and 1.2m apart and no closer than 60cm to the wall.

As a rough guide, divide the ceiling height by two to obtain the perfect spacing distance. So in an average home with 10ft ceilings, this would mean the downlights are spaced 5ft apart. This works well for residential properties, which typically have ceilings between 8ft and 10ft, but for higher ceilings, you’ll want to space them out a bit further, but you’ll need to add more, as the spread of light will also mean that the light hitting the floor is weaker, as it had further to travel.


Whether you’re looking for a simple answer to the question “how many downlights do I need in a kitchen?” or want to know more about how to place and space your lights, we hope this article has been helpful. Remember that there are many variables at play when it comes to lighting a room, so take your time, do your research, and get this done. If you are not sure about how to get this job done, call your local electrician.


How many downlights do I need calculator?

Here’s how you calculate the number of downlights you need for your room:
1) Calculate the area of the room (length x width in feet)
2) Estimate the required wattage (area x 0.3 for LED, 1.5 for halogen)
3) Find out the wattage of the bulb you’re using (10W LED = 42W halogen)
4) Calculate how many downlights you need (the area from step 2 divided by wattage from step 3.

How many downlights do I need per room?

It depends on the size and ceiling height of the room, as well as the wattage of the bulbs you’re using. Use our calculator to work out how many downlights you need.

How many downlights should I install?

Work out how many you need using our calculations, and then round up. You can add them in areas that need the most intense light or spread them evenly throughout the room.

How far apart do downlights need to be?

You should space your downlights evenly around the room, approximately 1m to 1.2m apart. For average ceilings (8-10ft), divide the ceiling height by two to determine the perfect spacing distance between each light.


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