Here we are going to discuss about power supply calculation.Power supply or smps which are used to give power to led. In power supply voltage and current ratings are there and multiplication of voltage and current is power whose unit is watt.
When we are going to market for power supply they ask what wattage and Amp of supply you want.for that you must know how to calculate current and power .
P = V*I.
Here P is power unit of power is Watt
I is Current whose unit is Ampere
V is Voltage unit is Volt
R is Resistance or Load unit in Ohm.
Before that you must know current consumption of your led.
Current consumption of one pixel led is About 60mA when it has 100% Brightness and white color.
Because in led the is only three main color red green and blue. Every colors are made by adding these three colors.
So red green blue consumes 20mA each for safe side assume 60mA for each led.
For example if you want 50 pixel so use 50×60mA = 3amp
For more details please watch this video