Grow Room Light Calculator: How Many Lights?

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Last Updated on March 9, 2023

One question mostly asked by hydroponic growers is how do I calculate my grow room light? It’s really quite easy to go about this when you have access to the right knowledge. So, this is why we’re going to be giving you the actual grow room light calculator to go about this.

Determining the appropriate light your grow light can cover is important so you can plan properly to get the best yield. Light is directly associated with production or yield; therefore, a feeble light will definitely not suit your plants’ growth.

We will introduce you to various ways to evaluate your grow light coverage using a grow room light calculator. So, continue reading to learn about this.

Grow Room

A grow room is a space where different types of plants can be grown and the growing conditions can be controlled. In a grow room, plants can be grown using grow lights or sunlight, artificial nutrient solutions, soil or non-soil medium, and so on.

Setting up your grow room will require proper planning and putting the right things in place. One of the most important things to put in place is the grow light and you must get the right to grow room light coverage.

Grow room

Grow Room Lights, Calculator

Grow room light calculator will help you determine the cost of power you will be using during the period of use. There are different ways or tools you can use in evaluating your grow lights’ power consumption. The calculator can be used for most grow light fixtures such as LED CMH, MH, CFL, and HPS.

To evaluate your grow room lights you will need to know some important parameters such as PPF (Photosynthesis Photon Flux) and actual wattage. These parameters are usually listed on the manufacturer’s info of your grow light.

Photosynthesis Photon Flux (PPF)

The entire amount of light in the PAR (Photosynthetic Active Radiation) zone that is emitted by a particular light system every second is known as PPF.

What this means is that PPF calculates the photosynthetic active photons produced by a light source every second. It is measured or expressed in micromoles per second.


The amount of electricity or power pulled out of or consumed from the wall is known as wattage (w). When we talk about wattage, there is a difference between actual wattage and labeled wattage.

On a grow light packing, you will likely come across the labeled wattage number that will be boldly seen. However, this may not be the actual wattage. What we need to evaluate grow room coverage is the actual wattage and this can be found if you dig through the information provided by the manufacturer’s data.

Apart from photosynthesis photon flux and wattage values, there are other parameters you can use in calculating the grow room light coverage. So, you can always calculate the grow room light depending on the information you have.

Using Grow Room Light Calculator

To determine the grow room light coverage, simply input your data and use these calculators to evaluate your results:

Note that the grow room light calculator mentioned above is just to have an estimate. Thus, the results that you will get are not the exact evaluations.

Factors to Consider For Grow Room Coverage Calculator

To make your evaluation further accurate, you should put these factors into consideration:

  • Determine the size space or grow room size you will be growing in.
  • You should also ensure the grow light you will be using adequately covers your grow space with adequate light. The grow light efficiency should be optimal.

VIVOSUN 48” x 48” x 80” Hydroponic Mylar Grow Tent with Observation Window and Floor Tray

Calculating LED Wattage of a Grow Room

Let’s determine the LED grow light size you will be needing for a particular grow space so your plants can grow excellently. So, to determine this, we need the value of grow light in watts and PAR or PPFD levels.

Even though we use wattage as one of the criteria to determine the power of light, it is not the main deciding unit. The determining factor of light will be the amount of usable light that can reach each square foot of your grow area or space.

In general, the main objective for LED panels should be 32 wattages per square foot of a growing area. This will increase your chances of getting excellent plant growth results.

To evaluate the actual value of wattage needed for a grow room, first determine the size of your grow room. Then go ahead and multiply the value by your desired PPFD range. Then divide the output by the PPFD per wattage of your LED grow light.

You should however note that watts are not the only determiner of your coverage area. Wattage should generally be used for determining the appropriate light fixture size for your grow room. Only use wattage as guidance to evaluate how much power your grow light can offer per square foot of growing space.

Calculating LED Wattage Of A Grow Room

For this reason, PPFD (Photosynthetic Active Radiation) and DLI (Daily Light Integral) are the right units for determining the light intensity of a particular grow space. DLI which is Daily Light Integral calculates the total amount of light a plant gets per day. It is measured using the number of moles of photons per square meter daily (mol/m2/d).

Grow Light Distance Calculator

Many factors determine how far the distance should be between your lights. Let’s take a closer look.

First, you’ll need to determine how far your grow light should be from your plants. Unfortunately, there is no one set answer. It all comes down to the variety of plants you’re growing, what type of light you’re using, and also how big your grow tent is.

You may think it’s strange that the variety of plants can affect the distance your grow light should be from the plant, but it definitely does! For example, some plants can thrive in low lights; such as indoor plants. Whereas others like vegetables such as tomatoes need significantly more! Therefore the grow light would need to be much closer.

Other factors that will affect the distance are both the wattage of your lights and the size of your lights. Some grow lights are intense and focus on just one small area, whereas others cover a much larger surface area. It’s also worth mentioning that the higher wattage of your grow lights, produces larger amounts of light, and will determine how close you place it to your plants. You definitely don’t want your plants to burn!

Another aspect you need to consider is the growth stage of your plant. When your plants are new, like seedlings, it goes without saying that they require less light. However, the older they get, the more light they will need, so you’ll likely have to adjust the distance of the grow lights.

You need to calculate all of these factors before you decide how far away your plants need to be from the grow light, and how intense your light needs to be.

Grow Room Calculator Yield

To find out the yield of your grow room, there are many websites that you can use that are fairly accurate. One of my favorites to use is Indoor Yield-O-Rama. This is because it allows you to input the light wattage, the light intensity, your level of gardening expertise, and then which, if any, hydroponic media you use.

It then gives you the estimated crop yield, grows room size, and the amount of light you’ll need for your plants to thrive.

How Many Grow Lights Per Plant?

The amount of grow lights you’ll need for each plant you’re growing depends on several variables. For example, whether you’re growing high-light plants or low-light plants, what stage of growth your plants are at, the size of your grow tent, and how many watts you’ll need for your plants to thrive.

However, the general rule of thumb suggests that for every square foot, you’ll need around 40 watts if you’re using an LED grow light. And if you’re using an HID light, for every square foot, you’ll need around 62 watts.

Grow Lights

Final Say on Grow Room Light Calculator

Grow room light calculator will help you evaluate the light intensity required for a specific grow space. This will help you plan and give your plants the appropriate requirements for your plants to grow excellently.

So, you can simply go through our post to learn about grow room light calculator. We hope with the help of our grow light coverage calculator, you can plan and determine the required grow light coverage of your space.


How do you calculate grow room lighting?

A grow room may be equipped with one or more grow lights, and the wattage of these lights should match the number of plants you have in your room. Accordingly, one pant requires from 60 to 80 watts and 6 plants from 360 to 400 watts.

What size LED grow light do I need?

A grow light is a lighting system that provides light to the plants in your grow room. Grow lights can be classified into two different categories: fluorescent lights and LED lights. Fluorescent lights are generally used in indoor growing setups, while LED lights are often used in outdoor setups. The most common use for grow lights is to help promote flowering of your plants, but grow lights also play an important role in the vegetative stage of growth as well.
LED lights are becoming increasingly popular because they offer many benefits over fluorescent lights. They use less electricity, produce less heat, and can be used in any room without the need for ventilation. In addition to these advantages, LED lights are capable of producing multiple wavelengths of light, which means they can provide light in all the different colors of the spectrum. This makes them ideal for growing plants in a vegetative stage, as they can help your plants stay healthy and vibrant.

The ideal wattage for LED is 32-50 per square foot.

How close should light be to plants?

The answer is different depending on the plant and the type of lighting. There are a number of factors that you should consider when deciding how close your light should be to your plants, including:
the color temperature of the light the type of plant (light requirement) the height of the plant how much light the plant gets naturally the distance to any other lights in your room. If your plant gets less than 50% light from natural light, then it is important to keep the light as close to the plant as possible. In general, LED lights should be 6 inches over plants.

How do I choose LED grow lights?

LED grow lights are economical and long lasting. However, not all LED grow lights are the same. How do I know what to buy? What is the difference between an HID grow light, LED grow light and CFL? LED Grow Lights The light emitted from an LED grow light is narrow-spectrum, which means it emits a very specific wavelength of light.

This is important because your plants absorb this specific wavelength of light. You need to be careful when choosing an LED grow light that emits the right wavelengths of light. For instance, an LED grow light with a spectrum of about 650 nanometers will grow tomatoes, peppers, and cucumbers. The reason for this is that tomatoes absorb red light. Red light is a type of visible light that plants absorb and use as a source of energy. Blue light is a type of visible light that is reflected off plants. LED grow lights are also known as LED strip lights or light emitting diodes. They’re a great option because they last a long time. In fact, some LED grow lights are rated at 20,000 hours! That’s about 5 years of continuous use.

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