How Many Questions Are on the Iowa CDL General Knowledge Test?
50 questions. That count is fixed by 49 CFR Part 383, the same across every state — the Iowa DOT administers the federal format rather than writing its own.
What Iowa actually controls
The federal government owns the question count and 80% threshold. Iowa's own contribution is a $12 CLP fee that already includes the knowledge test itself — no separate testing charge on top.
Depending on the class and endorsements pursued, additional tests — like Air Brakes or Combination Vehicles — may also apply on top of the General Knowledge test.
A CLP with no renewal option
Once issued, an Iowa CLP is valid for one year, and there's no renewal period — if it lapses before you complete your CDL, you start the application over from scratch.
A full Iowa CDL, combining the $12 CLP fee and the $16 CDL license fee, runs about $28 total — among the lowest complete costs of any state.
How our practice tests are structured
Our practice tests break results down by topic immediately, so a weak spot doesn't stay hidden inside an otherwise decent overall score.
Each question includes an explanation and a source reference, so you learn why an answer is correct instead of just memorizing a letter.
Frequently Asked Questions
How many questions are on Iowa's CDL General Knowledge test?
50 questions, the federally standard length used nationwide, not an Iowa-specific number.
What does the Iowa CLP cost?
$12, which already includes the knowledge test.
Can an Iowa CLP be renewed if it lapses?
No — it's valid for one year with no renewal period, so you'd need to reapply from scratch.
Ready to put this into practice?
Start a free Iowa cdl practice testLast reviewed: 2026-07-22