How Many Lumens And Lights Do You Need?
With so many options to choose from, choosing the right light has now become a head-scratchingly confusing task.
Let us imagine a practical scenario.
When was the last time you went to a lamp store to buy new lights to replace the current lighting arrangement? If recently, Here is what you might have observed;
- There are now more choices in the conventional lighting like incandescent bulbs.
There are new technologies in the old technologies. You may now find full-spectrum incandescent bulbs.
(Point to ponder; full spectrum bulbs are usually the ones which render light in the daylight spectrum, which is generally better than so-called artificial lights.)
There are 60W incandescent lamps, which can easily touch a CCT of around 5500 kelvins. The lumen output of these bulbs, Chromalux Full Spectrum Lamp A19 60W Clear, for example, is around 690 lumens.
This bulb will cost you $6.
- You may find a 15-watt fluorescent tube with CRI 91, and brightness 610 lumens with an operational life of 15,000 hours.
It is going to cost you between $15-$17.
- You might also find a 9 Watt A19 LED Light Bulbs, with CCT of around 5000 kelvin. LED bulbs last up to 15,000 hours. This is going to cost you approximately $10.32.
How many lumens does one need to light up their room or hallway entirely?
Before we dive any deeper, let us make one thing clear.
Wattage can give a tentative insight into lumens, but there is no standard formula to calculate lumens from wattage. There is no defined lumen to watt conversion methods available as of now.
Every room and space has its own brightness requirement.
Both color temperature and brightness choice boils down to personal preference; there is a minimum to this scale. Beyond achieving the required brightness, an ideal distribution mechanism is also as important.
The amount of lights is always personal preference, just like the color shade of your wall. But at least minimum amount of required light and well distribution of light should be considered.
How Many Lumens Do I Need?
Do you have enough lights?
Let us help you out mathematically.
According to the IESNA Lighting Handbook: (Illuminating Engineering Society of North America) published in 1993, here are some lumens required per square foot.
Floors require 20 Lumens/Foot^2
Tables and Mounted Surfaces require 30 Lumens/Foot^2
Desks and Task Lighting require 50 Lumens/Foot^2
Here we would like to talk about footcandles.
According to Wikipedia;
A foot-candle (sometimes foot-candle; abbreviated fc, lm/ft2, or sometimes ft-c) is a non-SI unit of illuminance or light intensity. The foot-candle is defined as one lumen per square foot.
To get an even better idea of lumen requirement per here is a chart to explain things better. (fc stands for foot-candles). From credible sources like the IESNA Lighting Handbook, here are some rough foot-candle estimates.
- Home office: 60-80 fc
- Workspace or garage: 80-100 fc
- Kitchen work areas: 70-80 fc
- Hallway: 5-10 fc
- Bathroom: 70-80 fc
- Bedroom: 10-20 fc
- Dining room: 30-40 fc
- Living room: 10-20 fc
- Kitchen: 30-40 fc
Some Practical Examples
How Many Lumens Do You Need In A Living Room?
For a living room with area 100 square feet, lumen requirement will be 100*(10fc-20fc)= 1000 lumens-2000 lumens.
Again, these are not standard rules, but these calculations are reliable for rough use.
If the table in your living room is 6 x 3 feet, then the total lumen requirement as per the IESNA Lighting Handbook is 30 df, so the total lumen requirement is 540 lumens.
If you enjoy reading, you might have a recliner or sofa in your living room; you would need at least four sq.Ft-6 sq.Ft, which requires task lighting (50 lumens per square foot), so overall lumen output you will need is 50*4-50*6=200 lumens-300 lumens
A 9 watt A19 bulb with CCT 4000kelvin and lumen output 800 lumens, will make a good choice for reading.
Just Another Example
For garage lighting, as specified above, needs around 80 lumens-100 lumens/sq feet.
One car garage area typically has a size of 12 feet wide and 22 feet deep, which is 264 square feet.
The lumen requirement in such places is generally around 264*100=26400 lumens.
Four T8 8ft V Shape LED Tube (2 rows of 2 8ft V Shape LED Tube arranged in parallel can be a great option) are enough to light up a one-car garage
The distance between fixtures should be equal to or no more than 1.5 times the height of the work surface.
How Many Lights Do You Need?
But remember, LED lights are one of the best lights for any of the lighting needs. LED lights can easily reduce the number of lights you used to use before.
A 9 watt A19 bulb can easily replace a 60-watt incandescent bulb or three 25W incandescent bulb.
The number of lights, though, depends a lot upon the number of tasks or different requirements. All of these assumptions and calculations are for 8-9 feet ceilings. Another addition to the number of lighting fixtures is generally a personal preference. If you need more flexibility with the number of fixtures available, consider installing dimmers along with the lights.