The amount of light you need for your indoor garden will depend on the size of your space and the type of light you use. Generally speaking, you want to provide at least 50 watts per square foot of growing area for optimal growth and yield. For example, if you have a 4x4 tent, you will need at least 800 watts of light to cover the entire area. However, this is just a general guideline, and different types of lights may have different efficiencies and outputs. For example, LED lights are more efficient and produce less heat than HID lights, so you may need less wattage to achieve the same results. The best way to determine how much light you need is to measure the light intensity at different points in your growing area using a lux meter or a PAR meter.