Grow Tent Carbon Filter Size Guide: The Ultimate Formula

So, you get excited and decided to start your grow tent setup until you get overwhelmed and confused by the various carbon filter sizes available online. Then you start to doubt yourself whether this indoor growing thing is for you or not. Don’t worry, you have come to the right place to know what exact carbon filter size is required for your grow tent.

What carbon filter size for a grow tent? To calculate the carbon filter size, you need to calculate the CFM of your grow tent and match it up with the carbon filter CFM guide. The size of the carbon filter could increase based on other critical factors such as the number of plants grown, plant species, and the power of the growing lights used.

Calculating what carbon filter size for your grow tent is a critical step for your grow tent to succeed. That’s why I created this easy guide for newbies to walk you through selecting the right carbon filter size for your grow tent.

How To Calculate The Right Carbon Filter Size?

A grow tent carbon filter size guide is essential for any indoor gardener to ensure they are purchasing the right-sized filter for their grow tent.

When selecting a carbon filter size, growers should take into account the size of the tent, the type of lighting used, and the desired CFM rating. The larger the tent, the more powerful the filter needs to be, and the bigger the CFM rating should be.

Step 1: Measure The Grow Tent Volume (LengthXWidthXHeight)

Use a measuring tape to measure the grow tent volume. You can find the dimensions written by the manufacturer on the grow tent package. However, double-checking the dimensions to get the most accurate measurements is critical.

Step 2: Divide The Grow Tent Volume By 3 (CFM Value)

The CFM (Cubic Feet per Minute) value tells you how much air in cubic feet your carbon filter can filter out in a single minute.

You need to divide the grow tent volume by 3 to get the actual grow tent CFM value.

Step 3: Calibrate The Final Value With The Grow Tent CFM Guide

Now that you have the actual CFM value of your grow tent, it’s time to calibrate the grow tent CFM value with the required carbon filter size.

CFM To Carbon Filter Size Guide

Grow Tent CFMCarbon Filter Size
0-400 CFM4-Inch
400-700 CFM6-Inch
700 CFM and above8-Inch
Grow Tent CFM Size Guide

Grow Tent Carbon Filter Size Guide

Grow Tent SizeCarbon Filter Size Best Carbon Filter
2×24-InchVIVOSUN 4 Inch Air Carbon Filter
3×34-InchVIVOSUN 4 Inch Air Carbon Filter
4×44-InchVIVOSUN 4 Inch Air Carbon Filter
4×88-InchAC Infinity Air Carbon Filter 8″
5×56-InchiPower 6 Inch Air Carbon Filter
10×108-InchAC Infinity Air Carbon Filter 8″
Grow Tent Carbon Filter Size Guide

If you are wondering which carbon filter is going to best suit your grow tent, you can check the guide that I wrote discussing the top best carbon filters available on the market.

Factors That Affect Carbon Filter Size

The size of the carbon filters used is determined by several factors, including the plant species, the grow lights used, the humidity levels, grow tent size, and the temperature.

Grow Tent Size

Large-size grow tents are far better and way more practical than smaller ones. It allows you to raise more plants and produce more yield. Although larger size tents would require larger carbon filter sizes, it wouldn’t be a great issue since the tent is large enough to accommodate large filters.

The problem lies in the smaller size of grow tents. Small grow tents will still accommodate a carbon filter inside. However, it will occupy an average of 15% to 25% of the internal space of a grow tent.

To solve this problem, you can check out the step-by-step guide to placing a carbon filter outside of a grow tent.


Controlling the internal temperature is key to having optimal growth conditions. Some areas where the temperature is high can reach extreme levels, especially in the summer. These areas would dramatically lead to raising the internal temperature of a grow tent.

A solution for this is to place a carbon filter with a higher capacity than the normal required size to get more air out per minute. A carbon filter with high CFM is very important in these situations to avoid getting your plants wilted when you are out during the day.

Grow Lights Used

There are various grow lights used by indoor hobbyists.

  • LED
  • HPS(High Pressure Sodium)
  • Metal Halide

LED growing lights are fine with us and will produce minimal heat during operating hours. However, HPS and metal halide lights are the real problems.

These lights tend to produce a lot of heat when they are running. This produced heat could increase to higher levels especially when the used grow lights do have higher watt power than the required grow light size.

So, make sure to take the grow lights aspect into consideration before deciding to buy the carbon filter.

Plant Species

Plants species have a direct effect on the odors inside a grow tent, and it is important to understand how they interact to create a pleasant environment. Different plant species have different odors that can be either pleasant or unpleasant.

Different plant species also have different growth rates, which can affect the overall smell of the grow tent. Plants with fast growth rates can produce more odor-causing compounds, while slower-growing species may produce less.

Plant species will greatly impact the lifespan of a carbon filter, you can know more about how long will a carbon filter last in this article.

The type of soil used in the grow tent can also affect the smell. Soils with higher organic content can produce a richer, earthier smell, while soils with a lower organic content can produce very little smell.

Plants that produce more odors than others will require a larger carbon filter size to filter more per minute.

Relative Humidity

Relative humidity can have a significant effect on the odor in a grow tent. High humidity levels can increase the intensity of odors, making it difficult to adequately clean and ventilate the grow tent.

It can also lead to increased microbial growth, leading to an increase in mold and bacteria levels. Low humidity levels can also lead to a decrease in odor, as the moisture content of the air decreases, reducing the intensity of the smell.

A major issue that a lot of new growers tend to face during their first few months of using a grow tent is getting their carbon filter clogged. High humidity is the reason why a carbon filter can get clogged as the water vapor in the air adsorb to the carbon particles preventing odor molecules from getting adsorbed.

You can read more about how to solve a clogged carbon filter in this article.

Proper humidity levels in a grow tent also help ensure optimal growing conditions for plants, as the right humidity can optimize transpiration and photosynthesis. Proper ventilation and dehumidification systems can help maintain the right balance of humidity in a grow tent while filtering out odors and improving air quality.

Best Place To Put A Carbon Filter In A Grow Tent

The best place to put a carbon filter in a grow tent is in the corners opposing the ventilation fan

This is the optimal position for two main reasons: The first one is leaving more room for them to grow lights. The grow lights will be suspended from the ceiling at the center of the tent.

Carbon filters tend to occupy a larger space. Having carbon filters beside the grow lights will prevent light from directly reaching certain plants.

Moreover, a carbon filter needs to be opposed to the ventilation fan to allow air to circulate through the tent before outflowing through the exhaust fan.

Carbon Filter Size For A 2X2 Grow Tent

A 2×2 grow tent is an ideal size for beginning gardeners and those with limited space.

A 4-inch carbon filter is usually the right size for a 2×2 grow tent, as it is small enough to fit in the space and can effectively remove odors and pollutants. However, if you are using high-pressure sodium lights, it is recommended to go with a 6-inch carbon filter as it will be able to handle the increased heat.

If you are concerned that a carbon filter might occupy your already limited growing area, you can set up your carbon filter outside of the grow tent.

When selecting a carbon filter for a 2×2 grow tent, it is important to consider the type of lights you are using, and the expected temperature and humidity levels.

Moreover, it is recommended to buy a filter with a CFM value that is 20% higher than the calculated value to ensure that the filter is working optimally.

Carbon Filter Size For A 3X3 Grow Tent

The 3X3 size is the second most popular grow tent size used by newbies.

A 4-inch carbon filter will be more than enough to eliminate odors in a 3X3 grow tent.

This grow tent size have the capacity to grow up to 4 plants.

Carbon Filter Size For A 4X4 Grow Tent

This grow tent size will be operating at optimum rates with a 4-inch carbon filter. However, you do have the option to upgrade to a 6-inch carbon filter if you want to get an extra edge in eliminating stinky odors.

A 4X4 grow tent can accommodate up to 6 fully grown plants. The best aspect of a grow tent of such size is that you can start and experiment with using 1000-watt grow lights. The grow lights might be HPS or LED. However, if you are going to use HPS lights, make sure that you get the 6-inch carbon filter to increase the CFM rate and decrease the internal temperature at a faster pace

Carbon Filter Size For A 5X5 Grow Tent

This grow tent setup is the starting point for any grower who is trying to move from the beginner tier into the intermediate and advanced tiers.

The 5X5 grow tent will require a carbon filter with a minimum size of 6 inches. However, it is advised to use an 8-inch carbon filter because of the higher number of plants the grow tent can accommodate.

A 5X5 grow tent will accommodate an average of 10 fully grown plants. The high number of plants grown will definitely increase the process of odor production inside the grow tent. Moreover, a grow tent this size will need more than one grow light unit to cover the required space. Therefore, an 8-inch carbon filter could be the optimum solution for this grow tent size.

Carbon Filter Size For A 4X8 Grow Tent

The 4X8 grow tent will require an 8-inch carbon filter to eliminate its internally produced odors.

Both, the 5X5 and 4X8 grow tents, does have nearly the same properties regarding the growing lights and the number of plants grown.

Carbon Filter Size For A 10X10 Grow Room

The 10X10 is one of the most used growing spaces for professional indoor growers. This grow tent will need a carbon filter with a minimum size of 8 inches. However, more than one carbon filter and exhaust fan could be used to cover up a grow room this size.

A 10X10 grow room can accommodate up to 18 fully grown plants in a single growing cycle. A grow room this size will most probably be made inside a garage or an empty basement inside the house. One carbon filter and exhaust fan could not be enough to ventilate the amount of odors produced.

Also, there will be an increased amount of heat production due to the several grow lights that will be used. Some growers do use 2 exhaust fans combined with 2 carbon filters placed in separate places across the room to cover the wide growing area.


Selecting a carbon filter size that matches the exact needs of your grow tent is one of the major keys to success in indoor growing. All you need to do is calculate the grow tent CFM and match it up with the CFM to the carbon filter guide. However, there are several factors that might lead you to get a carbon filter that is higher than your grow tent needs.

Leave a Reply

Your email address will not be published. Required fields are marked *

Recent Posts