A Guide to Grow Light Calculators

Calculating grow light coverage can be complicated if you’re new to the world of indoor gardening. You might know that you need grow lights to enjoy a successful harvest, but you’re unsure just how many you need to buy to ensure your plants are adequately illuminated.

There can be a fine line between too much light and not enough, adding further weight to the idea that you must perform accurate calculations rather than relying on guesswork. And that’s where grow light calculators come in. Learn about what grow light calculators are, how to use them, and their benefits below. 

What Is a Grow Light Calculator? 

A grow light calculator is a scientific and accurate way for gardeners to compare different grow light brands. They can also help you analyze the differences between all grow lights on the market based on factors like coverage area, watts, photosynthetic photon flux (PPF), and harvest potential.

However, all grow light calculators work differently. Some allow you to enter your own data from the product descriptions of grow lights you see for sale online. In contrast, others provide calculations from pre-loaded grow lights your chosen business has in stock. 

With the former option, you can enter the information you have, and the calculator will fill in the gaps of the data you don’t yet have, such as cost efficiency, how much light you need, and the grow light quantity you require. 

Can You Find LED Grow Light Coverage? 

Before LED grow lights became more popular and common, most people used to calculate how many grow lights they needed based on the common knowledge that plants with flowers required between 20 and 30 watts per square foot. 

It’s now no longer as straightforward as that since LED grow lights function differently. Adopt this calculation method, and you might be disappointed with the results. High-quality grow calculators can help you calculate LED grow light coverage when you input the data you find on the packaging or product descriptions, and there’s no need to perform any complex calculations yourself.

As a general rule, you can also consider this approximate guide. 

Does a Grow Light Calculator Calculate HPS Grow Light Coverage? 

HPS grow lights are generally not as popular as LED lights, but some gardeners still use them. They can enjoy a wide range of benefits with HPS grow lights, such as radiant heat to mimic a warm climate, excellent light spectrum, ease of use, and cost.

While many calculators only perform LED grow light calculations, some can also calculate how many HPS grow lights you need to support your unique setup. If you have a traditional grow room, you might also find the information you’re looking for in this guide below.

How to Use a Grow Light Calculator

How you use a grow light calculator can depend on the calculator and the data it asks for. We recommend following these basic steps below. 

1. Visit a website offering a grow light calculator, such as Indoor Grow
2. Write down all relevant information from grow lights you’re interested in. For example, if you were looking at energy-efficient LED panel grow lights, you would read the specifications to find the information you were looking for, such as: 

• Power – 600 watts
• PPF - 1650 (μmol·s-1)
• Efficacy - 2.7 (μmol/j)
• Light Distribution - 120°

3. Enter some or all of this information into your preferred calculator. The empty fields for usable PPF and fixture coverage should fill in automatically. 

For this particular LED panel grow light, you could expect:

• Usable PPF of 1210 μmol
• 18.6 square-foot/1.73m2 fixture coverage
• Harvest potential of 665g/23.8 ounces to 907g/32.4 ounces

If you don’t have a preferred grow light in mind, you can follow these steps: 

1. Visit a website offering a grow light calculator, such as Indoor Grow
2. Enter your grow space into the calculator
3. Learn your usable PPF
4. Find a comparable grow light 

For example, if you entered a grow space of 4 x 4 feet to achieve 16 feet of growing space, you would need a usable PPF of 1040 μmol. 

Benefits of Using a Grow Light Calculator

It would be easy to visit your local grow light provider and pick grow lights within your budget. Still, there are no guarantees that they’ll suit your needs. By using a grow light calculator, you can enjoy some of the following benefits. 

Money Savings 

Calculating how many grow lights you need doesn’t have to be guesswork. If you guess and buy the wrong products, you’ve wasted your money and have to buy more/different lights.

Healthy Plants

Accurate calculations equal adequate lighting, and adequate lighting equals healthy plants. It’s a winning calculation! When you use a grow light calculator, you reduce the risk of providing your plants with too little or not enough light. 

A Perfect Match

Buy the most suitable grow lights for your grow space and needs. Grow light calculators also typically allow you to enjoy recommendations from leading businesses in the field. 

Perform Your Grow Light Calculations Today

As tempting as it can be to ‘wing it’ when it comes to grow lights, most experts recommend that you don’t! Enjoy healthier plants and superior light coverage when you use a grow light calculator in NZ to perform all the calculations needed to buy the right grow lights. 

Now might be the right time to explore your lighting options, input your data, and give your plants the best chance to thrive. 

What are the benefits of using a grow light calculator?

Benefits of using a grow light calculator include optimising plant growth, energy efficiency, and cost savings.

How do you use a grow light calculator to determine the number of grow lights needed for your setup?

To determine the number of grow lights needed for your setup using a grow light calculator, input the dimensions of your grow space and the type of plants you are growing. The calculator will provide recommended wattage and quantity of grow lights.