A sign setback is a required distance between a sign and a line the code names. “From the property line” is not enough on its own. You need two answers: which line (property line, right-of-way line, curb, or something else) and which part of the sign (face, post, or foundation).
How one real code handles it
Austin, Texas measures from the street right-of-way, not the property line, and sizes the setback to the sign's support in section 25-10-191 of its Land Development Code:
“A sign support more than 12 inches and not more than 24 inches in diameter must be set back at least three feet from a street right-of-way. A sign support more than 24 inches and not more than 36 inches in diameter must be set back at least five feet from the street right-of-way.”
The rest of the section fills in the ladder. A support 12 inches or less needs no setback, and one over 36 inches needs 12 feet. Any sign other than a wall sign within 12 feet of the right-of-way must be no taller than 30 inches or have at least nine feet of clearance underneath. And a sign that meets this section does not also have to meet the building setbacks set elsewhere in the code. So in Austin, the post diameter on your drawing decides the setback, and the building setback line is the wrong one to measure from. (Section history ends with Ord. 20170817-072. We read it on September 28, 2026.)
What to check on your job
Confirm where the line actually is. The curb is not a legal boundary. A right-of-way can be land the public owns outright or an easement across private land; FHWA illustrates both. Use the survey and recorded documents. Then check sight-distance areas and easements separately, since clearing the setback does not clear those.
See the setback measurement checklist for a site-plan workflow.