What's the Passing Score on the South Carolina CDL General Knowledge Test?
40 out of 50 — 80% — passes South Carolina's CDL General Knowledge test. That figure is set by federal regulation, applied identically nationwide, regardless of what the SCDMV does with its own regular permit test.
A federal number that happens to match South Carolina's own
49 CFR Part 383 fixes the CDL general knowledge test at 50 questions and 80% nationwide. South Carolina's own regular permit test also happens to use 80%, though at a different question count (30 versus 50) — the overlap in percentage is coincidental, not connected.
A missed attempt costs real money here: each retest of the knowledge test costs $2, on top of the $15 application fee already paid.
Building in a safety margin
Treat 80% as a floor, not a target — aim for 90%+ across all topic areas in practice, since a real exam under time pressure tends to run a few points below your practice average.
Our practice tests break your score down by topic immediately after each set, so a weak spot doesn't stay hidden inside an otherwise decent overall percentage.
The parts of the test that pull scores down
Air brake systems and hours-of-service limits are the two topics most likely to cost points, since both hinge on exact numbers (PSI thresholds, hour caps) rather than driving intuition.
Cargo securement sequencing is another common miss — remembering that the first check happens within 50 miles, then every 150 miles or 3 hours after, is easy to get backwards under pressure.
Read the explanation on every practice question, correct or not — it's what actually closes these gaps, not just re-answering until you get lucky.
Frequently Asked Questions
Can South Carolina require a higher passing score than 80% for the CDL test?
No. 49 CFR Part 383 fixes the CDL general knowledge test at 50 questions and an 80% passing threshold nationwide — the SCDMV administers that federal standard rather than setting its own.
What does a retest cost if I fail the CDL knowledge test?
$2 per retake, on top of the original $15 CLP application fee already paid.
What score should I aim for on practice tests?
Aim for 90% or higher consistently before your appointment. That buffer above the 80% minimum accounts for first-attempt nerves and any last-minute rule changes.
Ready to put this into practice?
Start a free South Carolina cdl practice testLast reviewed: 2026-07-21