Rush selecting an optimal hood that meets ventilation requirements is pretty much doomed. At best, you will just have to buy from a quality manufacturer based on some parameters we can suggest. It is much better to understand what requirements drive the parameters you end up with.

Rather than providing you with a pile of links to review, for which you may not have time, let's start with what size your cooktop is, whether it is gas or induction or electric coil, and whether you cook stir-fry and sear meat or just simmer stuff with your most prolific greasy plume coming from simmering bacon.

Thank you for your quick response. We will have a 30” induction range. The custom wood hood will be 36”. We rarely fry food, never bacon. Sometimes we stir fry. We mostly simmer, make soups, stews and roasts in the oven.

Alright. Let's assume that minimalist will do. I'm going to choose 60 ft/min (CFM/sq. ft.) as the required air flow rate into the hood aperture. How big is the aperture? Do you want an aperture that overlaps the front-to-back cooking zone, or just the back 18-inches, say, and anything to be cooked that is greasy or odoriferous gets cooked at the back?

Example: Wolf hood liner 34 x 22. (19" front to back is also available; calculated in parends.)

Effective entry area approximately 5.2 sq. ft. (4.5 sq. ft.) Multiply by 60 yields 300 CFM (270 CFM). These are actual CFM values, and blowers must be chosen to achieve these at various pressure losses due to baffles, ducting, and make-up air (MUA) restrictions. Simple approach for centrifugal blowers (not VaH squirrel-cage blowers) is multiply by 1.5 to get rated CFM, which calculates to 450 CFM (400 CFM). At these levels, local code enforcement might not require deliberate MUA, but some is a good idea for reasons you can search out on this forum.

Note that for more vigorous cooking (smoke point of hot oil), I would recommend 90 CFM/sq. ft.

Duct diameter should keep full power flow rate (300/270) air velocity in the duct between 1000 and 2000 ft/min.

An 18” or aperture should be fine

Then you can recalculate for 18 inches if you wish, or just use the 19-inch number for reference. There are many manufacturers of hoods. You tend to get what you pay for, and never get more than you pay for. With Wolf, you pay for US manufacture and long-term support. Lesser "quality" may well be acceptable in individual circumstances. I don't recommend hoods I haven't used, so Wolf is the only one I will comment on unless a hood configuration deviates from efficiency too far. Wolf also publishes a Guide with the dimensions, making it a convenient source for me to use for examples.

Any other questions?

Thank you so mush for your help. I will look at the Wolf guide.