How to calculate Grow Light Coverage

To calculate grow light coverage, you need to consider the light intensity requirements of your plants and the specifications of your grow lights. Here’s a general process to calculate grow light coverage:

1. Determine the light intensity requirement

   Different plants have varying light intensity needs at different stages of growth. This requirement is often expressed in terms of photosynthetic photon flux density (PPFD) measured in micromoles per square meter per second (µmol/m²/s). Research the specific light requirements for your plants or consult gardening resources to find the recommended PPFD values.

2. Determine the light output of your grow lights

   Check the specifications of your grow lights to find their light output. It is usually provided as the total output in terms of PPFD or the total photon flux emitted by the light source. Most of the Grow Lights provide PPFD map, for example FECiDA CR600 grow light PPFD map is as below:

3. Determine the Height of Grow Light

   According to the grow light PPFD map and your plants PPFD requirement, determine the height of your grow light. Generally speaking, the height should not be too low so that it may burn your plants, also should not be too high so that it cannot provide enough lights. You may choose a medium value.

4. Determine the coverage

   you may determine the coverage according to your PPFD map, the farthest position PPFD should match your plants minimum requirement. You may also calculate the coverage according to the grow light angle. Take a example of FECiDA CR1200 grow light, the angle is 120°, put the height 45cm, the diameter of CR1200 is 40cm, so the coverage = 1.15 * 45cm + 40 cm = 91.75

5. Lazy Instant Calculation

   The method above to calculate the coverage do cost some time. If you want an answer within seconds, here is a lazy instant method: wattage/30 per square feet. For example, a 120W grow light will cover 120/30=4 square feet(2×2 ft), a 270W grow light can cover 270/30=9 square feet(3×3 ft). The wattage here means the real power consumption. Anyway, it’s just a general method to estimate the coverage. You still need to calculate seriously according to the plants and lights fetures.