What Score Do You Need to Pass the CDL Test?
TL;DR
80% on each knowledge test. That figure is federal, set in 49 CFR 383.135, so it is the same in every state. It applies per test rather than as an average, and falling short on the air brakes or combination sections has consequences that go beyond a retake.
80%, and it is federal
49 CFR 383.135 puts it in one sentence: to achieve a passing score on each of the knowledge tests, a driver applicant must correctly answer at least 80 percent of the questions. Because it sits in federal regulation rather than state law, no state can pass you at 70% and none can demand 90%. If someone tells you the bar is different where they live, they are wrong about the score. What genuinely varies by state is how many questions the test contains, which we cover in a moment.
It applies to each test, not to your overall average
This trips up people adding endorsements. You do not get one combined score. Each knowledge test is scored on its own and each one needs 80%. So a driver going for a Class A with air brakes and tanker sits general knowledge, combination vehicles, air brakes and tanker, and has to clear 80% on all four separately. Doing brilliantly on general knowledge does not carry a weak air brakes result.
Two failures that cost more than a retake
Most of the time falling below 80% means booking another attempt. Two sections are different, and the regulation spells both out. Fail the air brake portion, meaning you score less than 80 percent correct, and if a CLP or CDL is issued to you it must carry an air brake restriction. That restriction bars you from driving a commercial vehicle equipped with air brakes, which rules out most tractor-trailers and a lot of straight trucks. The license is real but much less useful. Fail the combination vehicle portion, again below 80 percent, and you must not be issued a Group A CLP or CDL at all. There is no restricted version of Class A to fall back on.
- Air brakes below 80%: an air brake restriction is placed on the license.
- Combination vehicles below 80%: no Group A CLP or CDL can be issued.
- Every other knowledge test below 80%: retake it, subject to your state's waiting period and fee.
How many questions is 80% of?
The federal rule fixes the percentage, not the length of the test. 49 CFR 383.133 requires only that each test contain a set number of questions with a prescribed number drawn from each knowledge area, which leaves the count to your state. So the honest answer is that 80% might mean 40 correct out of 50, or a different number where you live. The percentage is the part you can rely on nationwide. Check your state's page or its licensing agency for the count, and practice to a comfortable margin above 80% rather than aiming to scrape it.