A lot of homeowners ask us how many CFM per square foot should you aim for. This is quite easy to answer using the 2 HVAC rules of thumb. Let’s explain how we can easily determine how many CFM per sq ft we need in HVAC. We will also solve a 2,000 sq ft home example to illustrate this, and look at a 100 sq ft to 5,000 sq ft CFM chart (from 67 CFM to 3,333 CFM airflow).
Namely, when sizing AC units, we use these 2 rules of thumb:
- 20 BTU per square foot (8 ft ceiling height). This means that 1 ton AC unit (12,000 BTU) can cover a 600 sq ft area.
- 400 CFM airflow for 1 ton of cooling output. This means that for every ton of cooling output, we have to use 400 CFM of airflow, as explained in detail here.
Now, if 1 ton AC unit can cover 600 sq ft, and 1 ton AC requires 400 CFM of airflow, we can easily calculate the average CFM per square foot like this:
CFM Per Square Foot = 400 CFM / 600 Sq Ft = 0.67 CFM Per Sq Ft
From this, we can clearly see that we need an average of 0.67 CFM per square foot.
Note: CFM stands for Cubic Feet per Minute.
Based on this, we can determine the how many CFM we need for 100 sq ft, 500 sq ft, 1,000 sq ft, 1,500 sq ft, and so on. In fact, we have calculated a chart for 100 sq ft to 5,000 sq ft CFM requirements (you can find it further on), but let’s start by looking at a 2,000 sq ft example:
How Much CFM Do I Need For 2,000 Square Feet? (Example)
Alright, let’s presume that you have 2,000 square feet home and want to figure out how many CFM you need for that.
Here, we can use the 0.67 CFM per square foot average and calculate the CFMs for a 2,000 sq ft house like this:
2,000 Sq Ft House CFMs = 2,000 Sq Ft × 0.67 CFM/Sq Ft = 1,333 CFM
This means we need 1,333 CFM for a 2,000 sq ft home. Quite a simple calculation when you have the information on how many CFM per square foot you need, right?
Here are the calculated CFMs for different-size rooms/homes, based on the 0.67 CFM per sq ft average:
CFM Chart For 100 Sq Ft To 5,000 Sq Ft Homes
| Square Footage (Area): | CFM: |
| 100 Sq Ft | 67 CFM |
| 200 Sq Ft | 133 CFM |
| 300 Sq Ft | 200 CFM |
| 400 Sq Ft | 268 CFM |
| 500 Sq Ft | 333 CFM |
| 600 Sq Ft | 400 CFM |
| 700 Sq Ft | 467 CFM |
| 800 Sq Ft | 533 CFM |
| 900 Sq Ft | 600 CFM |
| 1,000 Sq Ft | 667 CFM |
| 1,100 Sq Ft | 733 CFM |
| 1,200 Sq Ft | 800 CFM |
| 1,300 Sq Ft | 867 CFM |
| 1,400 Sq Ft | 933 CFM |
| 1,500 Sq Ft | 1,000 CFM |
| 1,600 Sq Ft | 1,067 CFM |
| 1,700 Sq Ft | 1,133 CFM |
| 1,800 Sq Ft | 1,200 CFM |
| 1,900 Sq Ft | 1,267 CFM |
| 2,000 Sq Ft | 1,333 CFM |
| 2,100 Sq Ft | 1,400 CFM |
| 2,200 Sq Ft | 1,467 CFM |
| 2,300 Sq Ft | 1,533 CFM |
| 2,400 Sq Ft | 1,600 CFM |
| 2,500 Sq Ft | 1,667 CFM |
| 2,600 Sq Ft | 1,733 CFM |
| 2,700 Sq Ft | 1,800 CFM |
| 2,800 Sq Ft | 1,867 CFM |
| 2,900 Sq Ft | 1,933 CFM |
| 3,000 Sq Ft | 2,000 CFM |
| 3,500 Sq Ft | 2,333 CFM |
| 4,000 Sq Ft | 2,666 CFM |
| 4,500 Sq Ft | 3,000 CFM |
| 5,000 Sq Ft | 3,333 CFM |
With this chart, you can now easily answer questions like this:
- How many CFM do I need for 500 sq ft? 333 CFM, as per the chart.
- How many CFM do I need for 1,000 sq ft? 667 CFM.
- How many CFM do I need for 1,500 sq ft? 1,000 CFM.
With the average CFM per square foot and this CFM chart, you can now quite easily determine how much CFM you need for your home. If you need a bit of advice about the calculations, you can use the comment section below, give us some numbers, and we will help you out.