What's the Passing Score on the Illinois CDL General Knowledge Test?

An 80% passing threshold on a 50-question test means you can miss up to 10 questions and still pass, but missing more than that means the test must be retaken.

Because this standard is set by federal rule (49 CFR Part 383) rather than by individual states, it can't be lowered by the Illinois Secretary of State — it's the same 80% threshold used almost everywhere in the country.

Since 80% is the minimum, a reasonable practice goal is to consistently score 90% or higher across all 17 CDL topic areas before your appointment, giving yourself a safety margin.

Our practice tests show your score as a percentage immediately after each set, along with a topic-by-topic breakdown so you know exactly which rules to review again.

Hours-of-service rules and air brake systems are consistently among the toughest topics, since they involve specific numeric limits and mechanical concepts that don't come up in everyday driving.

Cargo securement and pre-trip vehicle inspection procedures are also common weak spots, since they require memorizing multi-step sequences rather than a single rule.

Reviewing the explanation after every practice question, not just the correct answer, is the fastest way to close these gaps before test day.