If you are planning on install led strip lights (also known as ribbon LED) you should be able to accurately calculate the required power. Having inadequate power supply will cause only a few (or none) of the LEDs to turn on, or may cause flicker irritation. More specific power supplies will be more expensive to purchase, and will also be more difficult to install because of their larger size.
To calculate the power supply needed for your new led strip lights, you need to know: Length of strip or ribbon, Number of LEDs per meter, and Power consumption per LED. To calculate the size of the power supply (in Amps) you need to multiply the length of the LED band by the number of LEDs per meter and then multiply it by the LED power (0.08w to 0.24w per LED are typical values). Then divide the value by 12 volts to calculate the required Amperage from the power supply.
24 Photos Gallery of: Calculating Power Supplies for Led Strip Lights
We recommend that you add at least 10% to the calculated value to allow resistance and loss in the cable. You must also allow for possible additions or additions in the future. Most led strip lights can add additional sections using the connected cable. For each LED strip of more than 2 meters, you can feed 12volt to both ends of the strip or one feed in the middle, by cutting the strips in half and connecting the power supply to both strips.