Watts in light bulbs measure the amount of electrical power the bulb consumes to produce light. Think of it as how much energy the bulb uses, not how bright it is.
Historically, wattage directly correlated with brightness for incandescent bulbs. A higher wattage meant a brighter bulb. People were used to saying things like "I need a 100-watt bulb for this lamp." However, with the advent of energy-efficient lighting like LEDs and CFLs, this is no longer a reliable indicator of brightness.
The Shift from Watts to Lumens
The important thing to understand is that watts measure power consumption, not brightness. Brightness is measured in lumens.
- Watts (W): Measure the amount of electricity the bulb uses. A lower wattage means less energy consumption and lower electricity bills.
- Lumens (lm): Measure the amount of light produced. A higher lumen value indicates a brighter bulb.
Understanding the Change with Efficient Lighting
Traditional incandescent bulbs were inefficient, converting most of their energy into heat rather than light. Newer technologies, like LEDs, are much more efficient. They produce the same amount of light (lumens) while using significantly fewer watts.
Here's a table showing approximate equivalent wattages and lumen output for different types of light bulbs:
| Incandescent (Watts) | LED (Watts) | CFL (Watts) | Approximate Lumens |
|---|---|---|---|
| 40 | 6-8 | 9-13 | 450 |
| 60 | 8-12 | 13-15 | 800 |
| 75 | 13-15 | 18-20 | 1100 |
| 100 | 16-20 | 23-30 | 1600 |
Key Takeaway: When choosing a light bulb, focus on the lumens (brightness) you need, not the watts. This allows you to select an energy-efficient option without sacrificing the desired light level. The wattage will tell you how much electricity it takes to achieve that brightness.
In summary, watts in light bulbs indicate power consumption, and although previously an indicator of brightness with older technology, lumens are now the primary measure of brightness, especially with energy-efficient LED and CFL bulbs. Choosing lower wattage bulbs with similar lumen outputs will save energy and money.
