What is ideal Air to cloth ratio for woodworking dust collectors

I am in the middle of trying to figure out filter options for my cyclone. I have figured out the original air to cloth ratio for my Grizzly GO442 as 9.60/1 from dividing cfm by 226 sq feet of filter. This is the easy part. What is a good ratio ? Google from several sources has me from 3.5/1 all the way to 10/1. At least four or five other sources talk of the importance of getting this ratio right without telling you how to get it right. I have deduced this is a moving target because of all the variables in collection. How does one proceed to figure out a suitable ratio ? I would like a better idea before talking to sales guys who will tell me they have exactly what I need.

Mike, I'm in the process of designing my own dust collector, so have been researching this exact topic...

Bill Pentz's website says: "With typical 0.5-micron all polyester filters used for indoor air filtering we need about one square foot of filter area for every 4 CFM of dirty air. This means our 800CFM needed for good fine dust collection at our larger tools requires 200square feet of fine all poly filtering material"

That would be a 4:1 ratio.

Al-Ko makes some models that are highly-regarded (and highly-priced), and they publish specs on their max airflow, nominal airflow, and filter area (and I believe they use 0.5micron filter fabric, making this a good apples-to-apple comparison with Bill Pentz's data). Their models use 8 or 9:1, if you use "nominal" CFM (measured at 10" static pressure), or 13 or 14:1 if you use "max" CFM.

I found a presentation by an industrial baghouse manufacturer (https://www.iaom.info/wp-content/uploads/04kicefc18.pdf) that says:
7-10:1 General Suction
7:1 Secondary Collector
5:1 Centro-vac system

So, I'm designing mine for around 8:1, but I primarily decided that based on the physical size I want the filters to take up.

Mike, my Belfab bag house is about 6 to 1. A lot of variables here though. When I bought it they asked a lot of questions about ratio of coarse to fine material and hrs of usage. They then determined the correct number of filters.
It is important to get it right, we had a Murphy Rodgers 15 hp baghouse that the fan came apart and replaced it with a higher output fan and motor hoping it would keep up with the moulder better. It had better suction but the bags clogged quickly and the performance was worse till you spent some time cleaning the bags.
i would suggest trying to find a engineer that could help with this.

From American Fabric Filters: "Ideally, total CFM rating of the bag should be 50-100% larger than the rated air output of the unit." This is the bag on my old 600 CFM bagger which is a bit undersized due to my space restrictions at that time.

DC Bag Cleaned.JPG

Every 6 months or so I would turn it inside out and vacuum it with a soft brush head. The giveaway for when it needed cleaning is when the bag starts to look like a balloon when running versus this pic which is running right after cleaning. IIRC this bag is about 4 times the size of the factory bag. I ran a solid plastic bag inside the lower bag which used to breathe. This made this collector actually usable without blowing fine dust all over everything.

Glen I was just on their site looking at the chart for sizing bags. I noticed they had a different value for commercial applications. I will be contacting them tomorrow to see what they think. There is also a picture of a Grizzly cyclone before and after a conversion to bags.Thanks for the performance review on AFF 's bag filter.