Brightness and wattage are actually two different things. Lumens are the units used to measure light intensity or brightness, while wattage is a measure of how much power the light source uses. Since a light-emitting diode (LED) bulb uses as much as 90 per cent less electricity than a regular incandescent bulb, the LED requires only about 9 watts to produce a comparable amount of brightness to a 75 watt incandescent.
Check the packaging of your LED light for information about the brightness measured in lumens. Standard LEDS are available in a range of 50 to 1200 lumens of brightness. One lumen is equal to the amount of light a candle (standardised as one candela) lets fall on 1 square foot of area, 1 foot away.
Find information on the packaging about wattage. You may see two different wattage measurements for your light, stated in the format: "75 watt-equivalent, 9-watt LED." The watt-equivalent measurement shows you what wattage of incandescent light you would need to get approximately the same brightness as this LED. The real wattage (or power requirement) of the LED is much lower since LEDs use power much more efficiently than incandescent bulbs.
Compare your LED packaging to an incandescent bulb meant for the same application. If the incandescent bulb packaging doesn't contain lumen information, you can roughly convert watts to lumens based on the fact that incandescent lamps produce between 8 and 21 lumens per watt of power. One LED produces about 20 lumens per watt, but LEDs are almost always sold in clusters within one lamp. Also, LEDs last much longer than incandescents and don't waste as much heat energy.