Lumens per Square Foot – What Do You Need?

Appropriate lighting is crucial in any space, so to guarantee your favorite hangout spots are optimally illuminated, it’s essential to be aware of the amount of lighting required; when either remodeling a room or creating one from scratch.

How much light depends on the activity intended for each space, with this light intensity calculated by lumens per square foot. Our guide outlines everything you need to know.

What is Lumens per Square Foot?

Lumens per square foot is a measurement of the amount of light produced in an area. It measures how bright your room will be and indicates how much light should be used to properly illuminate it. The higher the lumens, the brighter your space will be.

For example, if you want to create an office or workspace, you would need more lumens per square foot than a living room. The number of lumens required depends on the purpose of the space and during the day how much natural light is available in the area.

How to Calculate Lumens per Square Foot

Calculating lumens per square foot is relatively simple and straightforward. All you need to know is the size of the room and how bright you want it to be.

Measure the Room

Begin by calculating the square footage of your space:

• Measure the length of your space
• Measure the width of the room
• Multiple the length with width to calculate the area

For example, a bathroom could be 8′ x 8′ (8 foot x 8 foot) which equals 64 square feet.

Choose a Recommended Brightness Level

There are recommended brightness levels for each space according to the most common activity performed within it.

These brightness levels are quantified by the amount of light that reaches a surface (usually the floor) within that space, measured in either foot candles in imperial or lux in metric.

Knowing how much light that needs to reach a surface per square foot, is important to help us calculate much much light will need to be created.

Differing states and countries vary in their recommendations, but here are some common recommended foot candle intensities of light:

• Kitchen: 30-40 foot candles (300-400 lux)
• Kitchen counters: 70-80 foot candles (700-800 lux)
• Bathroom: 70-80 foot candles (700-800 lux)
• Home office: 60-80 foot candles (600-800 lux)
• Dining room: 30-40 foot candles (300-400 lux)
• Living room: 10-20 foot candles (100-200 lux)
• Bedroom: 10-20 foot candles (100-200 lux)
• Hallway: 5-10 foot candles (50-100 lux)
• Garage: 80-100 foot candles (800-1000 lux)
• Games Room: 40-50 foot candles (400-500 lux)
• Commercial Space: 50-75 foot candles (500-750 lux)
• Workshop: 100-150 foot candles (1000-1500 lux)

Quick tip: Converting Foot candles to Lux is approximately done by multiplying the value of Foot Candles by 10.

Learn to convert lumens to footcandles.

Calculate the Lumens Required

Now that you know the square footage of your space and chosen a recommended brightness level for your room, you can calculate the amount of lumens of light that will need to be created from your chosen light fittings.

To do this simply multiply the square footage of your room by the appropriate light intensity to determine how many lumens are needed.

• foot candle unit x size of room

For example, let’s continue with the bathroom that measures 8′ x 8′ (64 square feet).

A bathroom has a recommended 70-80 foot candles, per square foot of space.

• 64 sq ft x 70 foot candles = 4480 lumens.
• 64 sq ft x 80 foot candles = 5120 lumens.

The recommended amount of lumens required is between 4480-5120 lumens.

Recommended Lumens by Room

A quick guide of how many lumens are required by type of space offers an easy starting point for choosing the right lighting for a space. It is of course dependant on the size of the room.

• Kitchen – 4,000-6,000 lumens
• Living Room – 2,400-4,000 lumens
• Bathroom – 3,500-5,000 lumens
• Bedroom – 1,800-2,700 lumens
• Hallway – 1,200-1,400 lumens
• Garage – 3,000-4,000 lumens
• Game room – 4,500-6,500 lumens
• Commercial Space – 7,500-10,000 lumens
• Workshop – 10,000-20,000 lumens

Check out our quick fire guide on how bright should a light be.

Choose the Lighting

The amount of lumens calculated per square foot now gives you the total lumens required for your space. This can now be used to determine what type of light fittings and bulbs are needed to achieve this desired level of brightness.

For example, our bathroom requires approximately 4500-5000 lumens, so this could be made up:

• 5 qty recessed ceiling lights each 800 lm = 4000 lumens
• 2 qty 470lm wall lights each side of a mirror = 940 lumens
• Total 4940 lumens

Now that you know how to calculate lumens per square foot, you’ll be able to choose the right lighting for your space. Check out our lighting ideas on how best to light a space, as there is way more to good lighting design than just achieving a brightness level.

Whether you’re looking for task lighting or mood lighting, understanding what levels of light are necessary will help create a comfortable and inviting atmosphere in any room.

Andrew Orange, the owner of Orange Lighting qualified and worked as an interior designer in 1993 before specialising in lighting working on high profile projects based in London. Since starting Orange Lighting Ltd in 2003 he has been sharing his knowledge and unique teaching style mostly to his designer clients, offering practical real life advice born from running a busy consultancy and lighting supply business. Launching in 2020, his blog has evolved into Quick & Easy Lighting, curating some 25 years design experience into making the lighting choice and design process achievable and easy to understand for all.