How to Calculate Kitchen Range Hood Fan Size

Range hoods are a necessary part of your kitchen set up. A hood range keeps your kitchen running efficiently: it removes odor, steam, smoke, and oil fumes that occur naturally when you’re cooking. It also removes excess heat to keep your home temperature regulated. And with a variety of styles and sizes available, it can even improve your home value. 

But despite the benefits, many homeowners turn a blind eye to the range hood. For starters, searching for the right kitchen hood can be overwhelming. After all, there are several factors to consider, such as the size, mount style, and ventilation type. But for this post, we’re focusing on how to calculate your kitchen range hood fan size. 

One thing you should know before reading on is that range hood power is measured in cubic feet per minute (CFM). The CFM plays a factor in determining the right size for your range hood. With that in mind, read on to learn more about choosing the best hood size: 

Why is fan size so important?

The right range hood size is important for a variety of reasons. If you over-dimension, you might spend more than you need to. And furthermore, if the height isn’t correct, your hood won’t perform as efficiently. If you don’t choose the right size for your range hood, you could find your head constantly grazing the base—which can be uncomfortable and ineffective. 

Different Types of Range Hoods

Wall mounted hoods are ranges against the wall, with the duct work hidden behind it. Island hood ranges hang from your ceiling directly over your island countertop. 

Range Hood Width

Range hoods should be the same as your stovetop, or just slightly larger. If you decide to go with a hood range that’s larger than your stovetop, be sure that it extends equally on both sides. The standard for larger hood ranges is three inches. For example, if you have a stovetop that is 36 inches, you might have a hood range with a 42-inch width. Generally speaking, you’ll need at least 100 CFM for every 12 inches of stovetop. So, for 36-inch stovetop, you’d need a range with a CFM of 300 minimum. Be sure to measure your stove top to ensure all burners are carefully covered. 

Range Hood Height

There are a few things to consider when it comes to range hood height. For starters, there should be anywhere between 30-36 inches between the base of the stovetop and bottom of the hood. Hanging any higher than 36 inches could hurt your warranty, and may even affect your hood’s functionality. If you have an island range or would like your hood range to extend to the ceiling against the wall, calculate the height of your ceiling, subtract it by the countertop height, and then subtract 36 inches. The resulting number is your ideal hood height. 

Range Hood Depth

Understanding the depth for your range hood is quite simple. Start by measuring the depth of your cooking surface, and then subtract between 2-3 inches—while still ensuring full burner coverage. The better the coverage, the more effective the hood will perform. Still, you need a little leighway. This prevents you from bumping your head while you cook.

Gas Stoves & BTUs

The aforementioned calculations are based on electric stove heat emissions. But gas stovetops yield more heat than their electric counterparts, which means they require higher levels of CFM. 

kitchen table with grey chairs in a white kitchen

The heat output and power in gas stovetops is measured in British Thermal Units (BTUs). To help you understand BTU, it helps to break down this equation into simpler terms. One BTU produces the amount of heat and power needed to increase the temperature of one pound of water by one degree. Gas stove tops are measured in BTU per hour. 

Search the label on the back of your gas stove to find your BTU. If the label isn’t there, or if it’s too faded to read, you can do a little research and math to come up with the number yourself. Ultimately, once you have an understanding of the BTU, you’re in a much better position to pick the perfect size for your hood range. 

Working with a Specialist

Understanding how to calculate your size is a great starting point for research purposes. The more you understand about the range hood size, the better off you are when it comes to search for the right range hoods online. However, it’s important that you work with a specialist for installation. Furthermore, your HVAC specialist or contractor will ensure that you have the right CFM for your hood, and that it adheres to local code. 


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