Blood alcohol concentration — Tennessee Permit Test

Blood alcohol concentration on the Tennessee permit test — 6 rules, each with the reason behind it and a question on it while it is fresh.

The rules

Blood Alcohol Concentration (BAC) is the percentage of alcohol in your blood; the higher the number, the more impaired you are.

BAC is the number police and courts use. Knowing what it measures helps you see why every drink pushes it up.

Blood Alcohol Concentration (BAC) is a measurement of the percentage of alcohol in the blood.

Tennessee Comprehensive Driver License Manual, p.79

A BAC of .08 means that for every 10,000 drops of blood in your body, there are 8 drops of alcohol.

It takes only a few drops of alcohol among thousands of drops of blood to make driving deadly.

This means that for every 10,000 drops of blood in a person’s body, there are eight drops of alcohol.

Tennessee Comprehensive Driver License Manual, p.79

Drinking 3 drinks in 1 hour affects you more than drinking 3 drinks in 3 hours.

Drinking fast gives the liver no time to catch up, so your BAC climbs higher than the same drinks spread out.

Drinking three drinks in one hour will affect you more than drinking three drinks in three hours.

Tennessee Comprehensive Driver License Manual, p.79

The heavier the person, the more alcohol it takes to raise the BAC.

A smaller friend who keeps up drink for drink with a bigger one gets drunk sooner and may not notice.

The heavier the person, the more alcohol it takes to raise the BAC.

Tennessee Comprehensive Driver License Manual, p.79

Drink for drink, if two people weigh the same, the one with more body fat will show signs of intoxication first.

Alcohol mixes with water in the body, not fat. Less water means the same drink is stronger in your blood.

So, drink for drink, if people weigh the same, the one with more body fat will show signs of intoxication first.

Tennessee Comprehensive Driver License Manual, p.79

A 12-ounce bottle of beer has about the same amount of alcohol as a 1-ounce shot of whiskey.

People think beer is the safe choice. One beer carries about the same alcohol as a shot, so it raises your BAC just as much.

The amount of alcohol in one (12 ounce) bottle of beer is about equal to that in a (1 ounce) shot of whiskey.

Tennessee Comprehensive Driver License Manual, p.83

On the test

What does Blood Alcohol Concentration (BAC) measure?

The percentage of alcohol in your blood. BAC is the number police and courts use. Knowing what it measures helps you see why every drink pushes it up. Tennessee Comprehensive Driver License Manual, p.79: “Blood Alcohol Concentration (BAC) is a measurement of the percentage of alcohol in the blood.”

How this works

Most practice tests hand you a bank of questions and leave the manual somewhere else. This one puts them together.

You read one law and the reason behind it, then answer a question on that law while it is still fresh. Get it right and you move on; get it wrong and you have found the gap while it is cheap to fix, not on the morning of the exam.

Learning one rule at a time, and proving it immediately, is what turns a manual you skimmed into something you actually know — and it makes studying feel like getting somewhere rather than like waiting to find out.

What it costs

  • One payment, once — not a subscription. Nothing renews and there is nothing to cancel, for an exam you sit one time.
  • Free to start: a 10-question test and the first section of cards. No sign-up and no account.
  • Paying opens the rest of the cards, unlimited full-length practice tests, and retests built from exactly the questions you got wrong.
  • Every level up to Prepared — 3 tests passed in a row.
  • Do the work, fail the real exam, and we refund you.

All Tennessee permit topics

Where these come from

Every rule here is checked against Tennessee Comprehensive Driver License Manual, published by the Tennessee Department of Safety and Homeland Security, and against the state code itself. Last checked 2026-10-03.