I know that is a broad question with so many variables. It may be high if you are choosy about what you bid. It may be low if you bid on everything with out qualifying the customer. Do you have a rule of thumb?
When I had a crew and dealt mostly with sales and managing the business, 35-40% with little pre-qualification.
Now that it's me and my partner, and I usually only chase non- referrals when there is nothing else to do, more like 80%.
I recently went 1.5 years without giving any "free" estimates. That was fun while it lasted. The EZ Button.
Right now closing at a rate of 25%.
It's a been awhile since I looked at it, but generally if I don't get around 50% I start trying to figure out why. Most of the jobs we quote are referrals and that makes closing easier.