How Many Lumens Do You Need to Illuminate Your Space

LED lights are commonly used in residential and commercial projects, including outdoor roads, tunnels, facades, indoor offices, and shop floors. LED lights consume significantly less energy than fluorescent or incandescent lights, and their prices have dropped dramatically. If you plan to switch to LED lighting in your home or office, you may wonder how many LED lights or lumens are required to light up a room. To calculate the total lumens needed to illuminate a room, determine the room's square footage, determine the foot candles by room type or room purpose, and then determine the needed lumens. Several online tools can help you calculate the correct amount of lumens based on the room size, such as the lumens calculator by room size.

Lighting Terms

Lumens

“How many lumens do I need to light a room?” is a frequent question. Lumen output measures the brightness or light output emitted by a light source. A standard 100-watt incandescent light bulb produces around 1,500-1,700 lumens. This means 600 LED lumens provide the same light as 600 incandescent lumens. LED lights have a higher Color Rendering Index (CRI), meaning they more accurately reveal the subject's colors being lighted but do not provide more light.

Watts

Bulb brightness is not measured; it is the amount of electricity (or energy) a bulb consumes to reach its claimed brightness. Light sources such as LEDs, Fluorescents, Halogens, and Incandescents have different lumen-per-watt ratios. Below we will use lumens as a measurement to ensure we have enough light for a space.

Wattage Equivalence

Wattage measures the electricity or energy a light bulb consumes to produce its lumen output. The lumen-to-watt ratio varies depending on the type of light sources, such as LED, fluorescent, halogen, or incandescent bulbs. For example, a 100-watt incandescent light can produce 1,500 lumens, while a 10-watt LED light can achieve the same brightness level. LED bulbs may claim to have a wattage equivalent to incandescent bulbs. Still, the actual ratios may differ slightly even among different LED products. The table provides a lumen-to-watt chart for different types of bulbs.

Foot-candle

A foot-candle chart shows how many foot-candles of light humans need to perform tasks comfortably in different spaces. Based on human-centric lighting design principles, the IES recommends that lighting for washing dishes should provide 20 foot-candles of light at two feet, six inches off the floor, which is also known as the horizontal target. However, to determine the needed lumens per square foot, you need to know the room's square footage and desired foot candles. You can then multiply the square footage by the desired foot candles to understand how many lumens are recommended per square foot.

How to Calculate Total Lumens Needed?

To calculate the total lumens lighting chart needed, you need to follow these three steps:

1) Determine room square footage

To calculate the room's square footage, multiply the length and width of the room. For instance, if the room is 10 feet by 10 feet, then the room's square footage is 100 square feet.

2) Determine the foot candles by room type or room purpose

The number of foot-candles required varies based on the room type. For instance, bathrooms or kitchens require more foot candles than living rooms or bedrooms.

3) Determine the needed lumens

You can multiply the room's square footage by the required amount of foot candles to determine the necessary lumens for LED lights. For instance, a living room with an area of 100 square feet and a need for 10-20 foot candles would require 1,000-2,000 lumens, while a dining room of the same size requiring 30-40 foot candles would require 3,000-4,000 lumens. Remember that too many lumens can cause discomfort or even be blinding, so it is crucial to calculate the appropriate lumens for your specific space to ensure proper lighting without causing any harm.

Footcandle Requirements By the Room

For Commercial Spaces

For Residential Spaces

Lighting Calculating Formula

To determine how many light bulbs you need to illuminate your space, use the following formula once you know the required lumens.

bulbs=lumensBL stands for the number of lumens that a light bulb emits" refers to the number of lumens that a bulb produces, which is typically listed on the bulb's packaging. This measurement better indicates a bulb's brightness than its wattage. LED lights can produce the same light as traditional bulbs while consuming less power.

Usage Example: The Foot Candle Calculator

To use the foot candle calculator, follow these steps:

1. Suppose you want to illuminate an area of your house, such as your kitchen or kitchen counter and are planning the lighting for it.
2. For lighting requirements in a kitchen, the optimal lighting level is 108 lux for the whole kitchen and 538 lux for counters used for detailed tasks.
3. To calculate the area of your illuminated space, you need to determine its dimensions. For example, suppose your kitchen is a rectangle 4 meters long and 2.5 meters wide. In that case, you can calculate the area as the product of the length and width, which is 10 square meters.
4. A1 = 4 * 2.5 = 10 m^2
5. The counter is 4 meters long and 60 cm wide: A2 = 4 * 0.6 = 2.4 m^2
6. To determine the necessary lumens examples for a room, multiply the room area by the required number of foot candles. This will give you the total lumens needed to illuminate the space adequately. L1 = 108 * 10 = 1080 lumens; L2 = 538 * 2.4 = 1291 lumens
7. Choose the type of light bulb you wish to use, assuming you want a standard bulb that emits 800 lumens in the kitchen and a small LED light above the counter that emits 200 lumens.
8. To determine the number of bulbs you need, divide the total lumens by the bulb's efficiency and round up to the nearest whole number.

n1 = 1080 / 800 = 2 bulbs

n2 = 1291 / 200 = 7 bulbs

To adequately illuminate a kitchen, you will need two standard light bulbs that emit 800 lumens each for the entire space and seven LED lights that emit 200 lumens each specifically for the counter area.

Factoring in Lumen Lighting Variables

1. Include a footcandle multiplier in your lumens calculation if your ceiling is higher than 10ft.

Ceiling Height Variable

1. The formula for calculating the recommended footcandle multiplier is below: footcandles (fc) = cd ÷ h cd = candlepower h = distance between the lamp and the horizontal target.
2. This section is only relevant if your ceiling height exceeds 10ft. Suppose your ceiling height is below 10ft. In that case, you can use the Lumen Method and Lumen's calculator to determine the required light output for your space.

Wall Color Variable

If your walls and furniture are dark-colored or using light fixtures with shades, you'll need about ten extra lumens per square foot of space to light the area properly.

Lumens to Candlepower Conversion

The historical candlepower equals 1.02 candlepower. Candlepower is a measurement unit used to measure light intensity levels relative to the light emitted by a candle of a specific size and composition.

Lumen output = C/0.07958