Grow Room Fan Size Calculator with Size-wise CFM

Fans are an unbelievably significant part of growing cannabis indoors, as they help to disperse the fresh air coming in via your air filtration system while preventing any stale air from forming.

In this particular article, we will be briefly talking about the importance of fans in the grow room, factors to consider while getting your hands on a grow room fan and how to calculate grow room fan size. 

Let us get right into it!

Why Do You Need To Get Your Hands On Indoor Grow Fans? 

grow room ventilation calculator

Cannabis plants retain all of the carbon dioxides available around them, which is the reason why you will have to set up fans close to your plants. 

They deliver fresh air around the grow room, so the entirety of your plants gets a consistent flow of carbon dioxide. Therefore, your plants are not affected by stale air, which can cause diseases and humidity. 

With somewhat more airflow, your plants will be able to breathe much better and fresher air, further promoting photosynthesis, supplement absorption, and, for the most part increasing your plants’ strength. Also, the branches will grow stronger because of the wind resistance.

It implies that they will have the option to grow thicker, heftier flowers during the flowering time frame. You can keep your fans on for the whole time, or you can have it on an intermittent time, at regular intervals.

Factors to Consider When Calculating Grow Room Fan Size 

To get the calculation right, you need to consider some primary factors that would decide the requirement for your tent ventilation. You need to understand the factors that add to the necessities of wind flow in your grow tent.

Understand that for every grow area, and you need to get a fan with a CFM that can contribute and support the needs of your tent. That is the reason to consider every one of the conditions that will give your plants the best environment for their growth

Here are a few factors that you must keep in mind when calculating the grow room fan size.

Grow Room Volume 

grow room size calculator

Grow Room Volume, undoubtedly, is the primary factor to consider. It is the total space and volume that your fan needs to cater to. It is pretty much all space inside your grow room. 

At the point when you purchase any fan, it needs to replace all the air inside the Grow room. 

Also, it needs to replace it with natural air from outside. Furthermore, your fan will be responsible for an even flow of air inside your Grow area. 

To get the best in return, you should have a fan that can circulate this air along these lines. The CFM should never be too low so that it does not circulate or supply air that covers the whole Grow room. 

Simultaneously, the CFM of your grow fan should not be more as compared with the total volume of your Grow area. If so, it will end up affecting your plants.

Calculating CFM by Volume 

To get the precise CFM of your fan, use the components of the Grow area. Increase the height, breadth, and length of the tent to get the total volume. 

That is: 

CFM = Height x Breadth x Length 

The total volume of the tent needs to be equivalent to the CFM of your fan. 

For example, Your grow tent is a 10x10x7 feet tent that you are dealing with. Thus, the fan size will be:

Fan Size = (10 ” x 10 ” x 7 “)/ 1 Minute = 700 CFM

Note: Most fans are measured in Cubic Feet Per Minute (CFM). Hence, it is vital to measure the elements of your tent using ‘Feet’ measurements as compared to using ‘meters.’

Ducting Design and Length 

Ducting Design and Length are something that needs to be the subsequent factor to consider after the volume. Ductwork will regulate the volume of air that can go through them at a specific time. 

Ducting curves and length will influence your fan’s capacity. It is critical to consider your ducting design and length before you get your hands on any fan. 

A few of the commonly used ducting designs are:

Long ducting runs: Long ducting runs have a length of somewhat around 10 to 20 feet and approximately 3 to 6 bends. 

Medium ducting: You can expect a rather medium length of between 5 to 10 feet with 2 to 3 bends. 

Minimal design: They do not have any ductwork; thus, no bends around them. It is merely an opening where you place your fan directly to ventilate your Grow tent.

Calculation of CFM by Ductwork 

It would be best if you keep in mind that you will require an extra 1 percent of the fan CFM for every foot of ducting length. At the point when you wonder about the curves, you need to consider the angles. For every 90 degrees angle of curves, you will need an extra 20 percent of fan CFM. 

So, if you have a tent with ductworks of 5 feet and curves of 90 degrees, you will require a total of 25 percent extra CFM for your fan.

For example, If you have a 200CFM fan size, 

Fan Size The Considering Curves (3) = (200 CFM + (200 × 60%)) = 320 CFM

Fan Size The Considering Ducting (15′) = (200 CFM + (200 ×15%)) = 230 CFM

Air Requirement 

Before you choose any CFM fan, you need first to understand the amount of air you would be needing to supply to your Grow area every minute. As we mentioned earlier, CFM is the volume that your fan will supply to your Grow region per minute. 

It helps you understand how many minutes it would take to replace the whole air from your grow area. 

Calculating CFM via Air Requirement 

To calculate the CFM of your fan dependent on the air requirement, you need to get the complete volume of the air in your space and divide it with the number of minutes you would want to replace it with.

For example, If the room dimensions are 10 feet(L) X 10 feet(W) X 7 feet(H), then, at that point, the total volume will be 700 cubic feet. Also, assuming that it takes 2 minutes to take the whole air out, the calculation would be:

Fan Size = 700 cubic feet/ 2= 350 CFM

Grow Room Insulation 

grow room calculator ventilation

This is a fundamental factor to consider if your Grow room is in an area that is constantly exposed to the sun or less insulated. These include growing areas in the basements, attics, rooms facing south, or places upstairs. 

In any case, if your grow room is well insulated, you do not have to think about this factor. Rooms that do not encounter a lot of heat from their environmental factors are acceptable. 

The plan is to get a CFM that would keep an ideal temperature in your Grow room. 

Calculating CFM By Room Insulation 

If your Grow room is hotter than required, get a fan with 20 percent extra CFM. However, for the situations where the temperatures are low, get a fan with 15 percent less CFM than the total CFM. 

For example, Assuming your basic CFM is 200, 

Fan Size for hot places = (200 CFM + (200×20%)) = 240 CFM 

Fan Size for colder places = (200 CFM – (200×15%)) = 230 CFM

Carbon Air Filter 

A carbon filter drops the productivity of the fan in separating air from a grow tent. At the point when air is passed through a carbon filter, the speed decreases to a certain level. 

The job of a carbon filter in a grow room is to purge the air and remove any contaminations before they are passed through the air.

Calculating CFM via Carbon Air Filter 

Carbon filter decreases the degree of air extraction from your Grow tent by 25 percent. In this way, assuming you need to get the best from your fan, add 25 percent to the total CFM.

For example, Fan Size = (200 CFM + (200×25%)) = 250 CFM

Heat Sources 

Electrical appliances in your grow tent are a common source of heat abundance in your grow tent. A couple of these machines include lights and humidifiers. 

If you do not have coolers or air conditioners in your grow tent, you would have to factor in the heat delivered in your Grow tent by these machines. You need to measure the amount of heat you are experiencing from your Grow tent. 

Lights are a significant source of heat generation. The ideal way to manage it is to have a lighting system that has the correct wattage for your Grow tent.

Calculating CFM by the Heat Sources 

It is suggested that for each heat source in your Grow tent to add 10 percent of CFM. This will help in removing the extra heat that you might experience in your Grow room. 

If you have lights of 1000W and they are not cool in a 200 CFM Grow area, here’s how you can calculate it:

200 CFM + (200×10%) = 220 CFM 

Also, keep in mind to multiply the percentage by the number of lights you have. That will assist you with getting the perfect CFM for your Grow tent.

Grow Room Fan Size Calculator (Extractor and Intake Fan) 

For this section of grow room fan size guide, we will take you through a tent case of grow space, include some primary conditions, and work out the final size of both grow room ventilation fans of both exit and entry. 

For example, we have an 8x8x7 grow tent located in the basement, with an inline carbon filter set up with the 4 feet duct system. As the room is vast enough for ScrOG style training, there are 15 plants to grow (as per our size guide). 

At a specific phase of growth, there are four 600W HID lights, which are air-cooled. Also, apart from the light, there are be no other significant heat sources.

Extractor Fan 

How about we start with the grow room extractor and intake fan calculating formula?

Step 1: Calculate the Space Volume 

The first step is relatively basic. You must simply decide the unit. There are two kinds of them: the European Standard and the North American Standard. 

In the first one, the measurement is taken in Meter (m), and in the following kind, it is in feet (f). 

In this example, we will be sticking with the American Measurement System.

In this way, the volume of the tent will be:

Volume = 8 ” x 8 ” x 7 “= 448 Cubic Feet

Step 2: Measure The Air Replacement Time 

Let us consider that whatever fan we will be using will actually be able to replace the whole air of the tent/room within a minute. It decreases the complicacy of the calculation. 

Fan Size = Volume / Minutes to Empty The Air 

Therefore, 448 cubic feet/1 minute= 448 CFM (Cubic Feet Per Minute)

Step 3: Calculate Carbon Filter Allowance 

As we mentioned earlier, there is a 4″ carbon filter in our setup, which is in-built with the ducting. Moreover, the actual rate at which it will decrease fan productivity is 25 percent. 

Therefore, Fan Size = 448 CFM + (448×25%)= 560 CFM

Step 4: Calculate the Insulation 

The degree of insulation has a lot to do with the climate of the grow room or grow tent. 

For example, we have a grow set up in the basement, which is pretty cooler than what it is in the other room. Along these lines, we will consider a 15 percent in the required fan size of the grow room. 

Fan Size = 560 CFM – (560×15%) = 476 CFM

Step 5: Measure the Ductwork 

In a 8×8 grow tent setup with grow room ducting fan, we will be keeping the ducting limited to 10 feet (including the bends). 

There is no standard or something like that, yet how about we stick to that for calculation. Furthermore, for a few bends and adjustments, there are around two bends in the ducting. 

Hence, Fan Size = 560 CFM + (560×10%) + (560×40%) = 840 CFM

Step 6: Calculate the Lights 

Just like heat sources, lights will raise the CFM requirement by 10 percent each. Be that as it may, as we have an air-cooled HID light setup, it will not heat the space up. Moreover, we do not have to take it into consideration. 

Fan Size = 840 CFM + 0 = 840 CFM 

At last, the grow room extractor or exhaust fan recommends we go with a fan of 840 CFM in size.

Intake Fan 

Now that we are done with the grow room exhaust fan size calculation, how about we get some outside air through the grow room air intake fan now?

Whenever you have figured out the size of the exhaust fan, working out, the grow room intake fan size is relatively easy. 

There needs to be slightly less pressure present in the grow room. That implies you need to intake relatively less air as compared to what goes out. Therefore, the CFM of the intake or inlet fan can not be the same as the CFM of the exhaust fan.

The basic rule is, the intake fan will be 15 percent less potent than the exhaust fan size. In this way, from our past discussion: 

Intake Fan Size = 840 CFM – (840×15%) = 714 CFM 

Thus, the final is intake fan size is 714 CFM. Even though it might go amiss, a lot is dependent on the fan setup in grow room.

Quick Tips (for Grow Tent) 

There are a few kinds of grow tent sizes, and calculating the grow fan size can be a hectic cycle. Here in this section of the grow room fan size calculation guide, we will give you a ready-made fan size for basic grow tent sizes.

What Size Fan is needed for 2×2 Grow Tent

In a 2x2x6 tent, there is mostly one carbon filter, four lights of 400W (non-air cooled), no ducting within, and a passive air inlet system. Assuming you keep it insulated enough from the surroundings, 

Fan Size for a 2″x2″x6″ Grow Tent = (24 cubic feet/1 minute) x 1.25 x (1.2) = 36 CFM

What Size Fan is needed for 2×4 Grow Tent? 

In a 2x4x6 grow tent, there is usually one carbon filter, four lights of 600W(non-air cooled), 3-6 feet of ducting within, and a passive air inlet system. If you keep the room insulated enough from the surroundings, 

Fan Size for 2″x4″x6″ Grow Tent= (48 cubic feet/ 1 minute) x 1.25 x 1.05x 1.25 = 78 CFM 

What Size Fan is necessary for 3×3 Grow Tent? 

In a 3x3x6 tent, there is usually one carbon filter, four lights of 600W(non-air cooled), 6-8 feet of ducting within, and a passive air intake system. If you keep it well insulated,

Fan Size for 3″x3″x6″ Grow Tent = (54 cubic feet/1 minute) x 1.25 x 1.07x 1.25 = 90 CFM

What Size Fan is necessary for a 4×4 Grow Tent

At the point when it is about a 4x4x6 tent, you will have one carbon filter, four lights of 600W(non-air cooled), 8-10 feet of ducting within, and a passive air inlet system. If you keep the room insulated enough from the surroundings, 

Fan Size for 4″x4″x6″ Grow Tent= (96 cubic feet/1 minute) x 1.25 x 1.08x 1.25 = 130 CFM 

What Size Fan is required for 4×8 Grow Tent? 

At the point when it is about a 4x8x6 tent, you will have one carbon filter, four lights of 600W (non-air cooled), 10-14 feet of ducting inside, and a functioning air intake system. If the tent is well-insulated,

Exhaust Fan Size for 4″x8″x6″ Grow Tent = (192 cubic feet/1 minute) x 1.25 x 1.12x 1.25 = 336 CFM 

Inlet/ Intake Fan Size for 4″x8″x6″ Grow Tent = 285 CFM

What Size Fan is vital for 5×10 Grow Tent? 

At the point when it is about a 5x10x8 tent, you will have one carbon filter, four lights of 800W (non-air cooled), 15-18 feet of ducting within, and an active air inlet system. If you keep the room well-insulated from the surroundings:

Extract Fan Size for 5″x10″x8″ grow tent = (400 cubic feet/1 minute) x 1.32 x 1.16x 1.25= 765 CFM 

Intlet/ Intake Fan Size for 5″x10″x8″ grow tent= 650 CFM 

What Size Fan for 8x8x8 Grow Tent? 

When it comes to an 8x8x8 tent, you will have one carbon filter, four lights of 1000W (non-air cooled), 18-20 feet of ducting within, and an active air intake system. If you keep it well-insulated from the surroundings:

Extract Fan Size for 8″x8″x8″ grow tent = (512 cubic feet/1 minute) x 1.4 x 1.19x 1.25= 1066 CFM

Inlet/ Intake Fan Size for 8″x8″x8″ grow tent = 906 CFM

What Size Fan is necessay for 10×10 Grow Tent? 

When it comes to a 10x10x8 tent, you will have one carbon filter, six lights of 800-1000W (non-air cooled), 20-22 feet of ducting within, and a functioning air intake system. Assuming you keep it insulated enough from the surroundings: 

Extract Fan Size for 10″x10″x8″ grow tent = (800 cubic feet/1 minute) x 1.54 x 1.22x 1.25 = 1878 CFM 

Inlet/Intake Fan size for 10″x10″x8″ grow tent= 1600 CFM 

Boost The Grow Room/Tent Fan Life By Following These: 

You should know how significant is a fan in a grow room. Being a little cautious around a couple of things may help the life expectancy of these devices. Here’s how you can do so:

Try not to Mismatch Your Ducting and Fan Diameters. 

Ducting is, as of now, a genuine reason to cut the fan speed down. If your fan and the ducting system have a mismatched diameter, that is a much more dreadful situation.

For example, a mix of 6″ fan reducing to a 4″ ducting will interfere with the wind flow. 

Basically, make an ideal match between your fan diameter and the ducting measurement.

Induce Active Air Intake Instead of Passive 

If you are managing a medium-sized grow room or tent, a couple of air filter openings will not have the ability to drag enough of the natural air. For grow spaces higher than 8 by 8 feet or so, use an active air intake fan for grow space to maintain the air pressure and air supply. 

Also, figure out how to work-up an exhaust fan in grow space for maximum productivity. 

Use A Centrifugal Fan 

For smaller tents or rooms, squirrel-type grow fans are sufficiently solid. However, for larger spaces with more extraction power consumption, centrifugal fans are better choices. Indeed, these grow room fan calculator formulas.

Centrifugal fans are used according to the air cooling system, the ducting, and the carbon filter. It will filter your air, cool down the grow lights and ventilate the grow room air.

Protects from Bugs 

The intake fan is normally situated close to the ground area. It is because the air close to the ground is cooler in temperature. Yet, that also welcomes the chance of the entry of bugs, dust, and airborne germs. 

Keep your grow room fan setup protected by using a bug mesh on the inlet fans to dispose of this danger. It will also help in reducing the grow room exhaust fan’s noise to a certain extent. 

Control Your Fan Speed 

At various growth stages and various seasons, you have to induce distinctive air ventilation rates for your plants. For example, it needs to be higher in the vegetative stage as compared to the seedling phase. 

That can be possible with a fan speed regulator. A lot of fans these days come pre-programmed, with timers.

When Exactly You Care About Fan Size? 

A lot of you might be a know-it-all but, a little revision never hurts. Hence, let’s examine the importance of precise grow room fan CFM calculation! 

Growing Plants Demands More Airflow 

When plants are at the beginning phases of growth, the leaves are smaller in size. Thus, the carbon dioxide that they intake from the surrounding is not that much. A decent amount of airflow leaves the plants with abundant carbon dioxide.

Be that as it may, when they grow up, leaves become bigger, and the need for carbon dioxide increases. Physiological cycles like photosynthesis and transpiration occur to a higher degree. The necessary supply of carbon dioxide (for photosynthesis) and oxygen (for transpiration) raises higher. 

Thus, you have to vent a greater amount of carbon dioxide-rich air out and replace it with outside air to keep plants alive. For this, a grow room fan is a must.

To Evacuate Excess Heat 

Lights, lamps, and pumps are the heat sources in any grow setup. In a sealed grow room, they become a significant source of heat. If you keep the space unventilated, they will rapidly increase the temperature to 100+ degrees Fahrenheit. 

With such an ascent in temperature, plants will slowly and can capitulate to heat stress. Hence, getting your hands on a grow room fan is very important. 

We hope this guide turns out to be an asset for you. 

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