Home use: 2.5:1
Professional Cutting: 3-3.5:1 depending on wood
Never should you have a saw with more bar than engine. Why? It’s frustrating, it means more sharpening with no wood-cutting gain (long bar, but can’t bury it in the wood). I suggest for most people that a 14″ bar on a 35cc engine is plenty. Now, when I say “most people” I mean the guy that has a tree branch in his yard he wants to clean up, or a few apple trees to prune etc. For firewood a good saw would be an 18″ bar with a 54cc engine.
Here is an example of what you should have and what is actually out there.
Poulan 2375, 42cc w/18″ bar – 2.33:1 ratio
For home use it should be 16″ bar (2.625:1 ratio)
For firewood use it should be 14″ bar (3:1 ratio)
For professional use (not gonna happen) it should be 12″ bar (3.5:1 ratio)
I can vote for it that with a 12″ bar it rips, I’ve owned one and set it up like that. WAY faster than stock and an absolute delight to cut with despite being a cheap saw. It’s amazing how the “extra” length can really turn an ok cutting machine into a pig.
The only reason manufacturers sell these saws with such long bars is because they move off the shelf quicker that way. Think about it, ask someone what size saw they have and unless they are a saw nut like me, they will tell you how many “inches” it is – IE the bar length, not the engine size which is really what matters.