For a very long time, most people shopped for lighting by checking out the wattage on a bulb. Once compact fluorescent and LED alternatives for standard incandescent sockets became available, though, the game changed and it became necessary to convert lumens to watts and vice versa when switching bulb types. All three bulb types have wildly different energy consumption to light output ratios, so just looking at wattage doesn't help when choosing a replacement bulb if you're changing types.
What is a Lumen?
Lumens are the internationally recognized measure of brightness, and one lumen is supposed to be equivalent to the light from one candela at a solid angle. That means, basically, each lumen is one candle power of direct light. Since the brightness of the bulb is the important part of buying one, a lumens chart is a lot more universally useful than a wattage chart. It lets you compare all these factors to make the best lighting choice for any room:
- Light costs for bulbs and/or fixtures
- Power consumption levels and their associated ongoing use costs
- Light lifespans and warranties to determine how much the cost per hour of use, comparatively
Most of the time, LED fixtures like remote controlled ceiling lights wind up being the most cost effective because even when they are more expensive up front, they boast a low power consumption and long lifespan.
Difference Between Lumens and Watts
Watts are units of power consumption, and they are calculated via the amperage and voltage of a power source. That doesn't indicate brightness, apart from lights of the same type being able to be sorted by power use, because lights with different power to light ratios will produce different brightness ratings at the same power consumption.
How Many Lumens Does a Room Need?
There is no hard and fast rule about how to light a room, so it's more a question of how much brightness you need to be comfortable and what you are doing, since mood lighting and shop lighting are very different. Here are a few things to think about while planning your lighting purchase:
- A 40W incandescent bulb is about 450 lumens
- A 60W incandescent is about 800
- 100W outdoor bulbs are about 1600
Of course, the outdoor bulb has to be incandescent for this estimate to work. A 1600 lumen halogen light is actually 72W. If you are comfortable figuring out how to light a room with incandescent bulbs, it's easy to add up the lumen rating to determine what to buy for LED lighting. You'll probably find the higher color reflection index in LED lights provides clear sight at lower brightness levels, too.
Calibrating Your Estimate
You'll probably find the higher color reflection index in LED lights provides clear sight at lower brightness levels once you install and test them out. Keep that in mind as you shop, because spaces that need high visibility will not require as bright a light output. Start by shopping for a single fixture around the same lumen rating to replace an old incandescent light, it's probably the best place to begin with LED lights.