Knowing how to study for the ATDH starts with knowing what's on it. The Admission Test for Dental Hygiene is the American Dental Association's entrance exam for dental hygiene programs: 240 multiple-choice questions across six sections, scored 200 to 500. This guide breaks down each section, the time you get per question, the free official practice materials, and an 8-week study plan you can follow. It's written for pre-dental hygiene students applying to a program that requires or accepts the ATDH. A strong score can set your application apart, and dedicated ATDH prep is limited: Booster Prep is the one major prep company we found that markets courses for it, and 56 of the 63 recent test takers in our focus group used it. All facts were checked against the ADA on November 7, 2026.

Quick answer

Quick Verdict

Give yourself 6 to 8 weeks. Start with the ADA's free practice questions to find your weak sections, review biology and general chemistry from a standard textbook, and practice Perceptual Ability daily with a tool like PATBooster, because its six puzzle types are unlike anything in your college courses. Finish with timed practice for every section.

In detail

What Is the ATDH?

The ATDH is a computer-based admission test from the ADA's Department of Testing Services, taken at Prometric test centers. Dental hygiene programs use it alongside your GPA and prerequisites to compare applicants. Since September 1, 2023, you can test year-round on any day with an open appointment.

Not every program uses it. The ADA's 2026 program list shows 17 programs that require the ATDH and 17 more that accept it without requiring it. Check each program you're applying to before you register.

In detail

ATDH Sections and Timing

The ATDH has six sections, 240 questions and a total seat time of 290 minutes, including a 15-minute tutorial, two optional 15-minute breaks and a 15-minute survey. The table shows each section and the time you get per question, which is the number to practice against.

SectionQuestionsTimeTime per questionWhat it covers
Reading Comprehension4050 min75 secondsMain ideas, inferences, relationships among ideas, word meaning
Language Usage4030 min45 secondsSpelling, punctuation, word usage, grammar, syntax, style and tone
Quantitative Reasoning4045 minAbout 68 secondsAlgebra, probability and statistics, data interpretation, word problems
Perceptual Ability6045 min45 secondsApertures, view recognition, angle discrimination, paper folding, cube counting, spatial relations
Biology3030 min60 secondsCell and molecular biology, diversity of life, structure and function, genetics, evolution and ecology
General Chemistry3030 min60 secondsStoichiometry, gases, solutions, acids and bases, kinetics, thermodynamics, equilibria, atomic structure

Source: the ATDH User's Guide (March 2026). The two breaks come after Language Usage and after Perceptual Ability.

In detail

How the ATDH Is Scored

Each section is scored from 200 to 500. You also get two composites: the English Language Skills score (Reading Comprehension plus Language Usage) and the ATDH Overall score, the average of all six sections, rounded to the nearest ten. There's no passing score; each program decides what it wants.

The ADA set the original scale so the average section score was about 350, with a standard deviation of about 50, according to its User's Guide. There's no penalty for guessing, so answer every question. Some questions are unscored experimental items, and you can't tell which ones, so treat every question as if it counts. Scores reach your programs and your DENTPIN account within three to four weeks, according to the ADA's scoring page.

In detail

Free Official ATDH Study Materials

The ADA publishes three free resources, and they're the best place to start: a practice question set, a list of the textbooks its question writers use, and step-by-step instructions for Perceptual Ability.

  • ATDH practice questions. 38 questions covering all six sections, with an answer key. The ADA notes that these aren't reviewed to the same standard as live exam questions, so use them to learn the formats, not to predict your score.
  • ATDH reference texts. The list includes Campbell Biology, OpenStax Chemistry 2e (free online), Blitzer College Algebra, Bluman Elementary Statistics and The Blue Book of Grammar and Punctuation.
  • Perceptual Ability instructions. The official rules for each of the six puzzle types.

The ADA also says DAT review materials may help, and it shares its DAT reference book list. That makes sense: the DAT has the same Perceptual Ability question types, and our DAT sections breakdown explains each one in detail.

In detail

How to Study for Each ATDH Section

Study the science sections from a textbook, the reading and language sections through timed practice, and Perceptual Ability through daily drills. That's the short answer to how to study for the ATDH: each section needs a different approach.

Reading Comprehension

You get about eight questions on each 450 to 500 word science passage, so practice reading science articles quickly and noting the main idea of each paragraph. Questions test main ideas, inferences and word meaning in context. Some ask whether a statement is true, false or not covered by the passage, so stick to what the passage actually says, not what you know.

Language Usage

At 45 seconds per question, Language Usage is the fastest section, so the goal is recognizing errors on sight. Review comma rules, subject-verb agreement, commonly confused words (affect and effect, its and it's) and formal tone. The Blue Book of Grammar and Punctuation from the ADA's list is short and covers most of it.

Quantitative Reasoning

Expect algebra, probability, statistics, reading tables and graphs, and word problems. A digital calculator is provided on screen, according to the 2026 Candidate Guide, so practice with an on-screen calculator rather than your phone. Set up word problems on paper first. You'll get two note boards and markers at the test center.

Perceptual Ability

Perceptual Ability (often called the PAT) has the most questions (60) and the least time per question (45 seconds), and its puzzles don't match any college course. Practice it every day. Learn one strategy per type: tally the painted sides of each cube column by column in cube counting, unfold one crease at a time in paper folding, and compare the object's outline with each opening in apertures. Speed comes only from repetition.

Biology

Biology covers five areas: cell and molecular biology, diversity of life, structure and function, genetics, and evolution and ecology. If you've finished your college biology prerequisites, focus on review rather than relearning. Make a one-page summary for each area and quiz yourself on it.

General Chemistry

General Chemistry gives you 30 questions in 30 minutes, and the 2026 Candidate Guide says a calculator is provided here too, along with a pop-up periodic table. Focus on stoichiometry, gas laws, solutions, acids and bases and equilibrium, and work problems by hand. OpenStax Chemistry 2e is free and on the ADA's reference list.

Study plan

8-Week ATDH Study Plan

Plan on 8 weeks of 10 to 12 hours a week if your science courses are recent. Add 2 to 4 weeks if you're returning to chemistry after a break. This ATDH study plan is our suggested schedule; adjust the weeks to your weakest sections.

WeekFocusPractice
1Take the ADA practice questions untimed; list weak areasPerceptual Ability: learn all 6 types
2Biology: cell and molecular biology, geneticsPAT 15 minutes a day
3Biology: structure and function, evolution, diversity of lifePAT 15 minutes a day; 2 reading passages
4General Chemistry: stoichiometry, gases, solutionsPAT daily; Language Usage rules
5General Chemistry: acids and bases, kinetics, equilibriaPAT daily; Quantitative Reasoning word problems
6Quantitative Reasoning and Language Usage reviewTimed sections at real pace
7Weakest two sectionsTimed full sections back to back
8Light review; redo every question you missedOne full timed run of all 6 sections

For a longer, week-by-week version built for the DAT, which shares the science and Perceptual Ability content, see our 3-month DAT study schedule.

In detail

ATDH Study Tips

Time yourself from week 1, practice Perceptual Ability every day, and keep a mistake log. These habits matter more than how many hours you put in.

  • Practice every section at its real time per question (see the table above), not just untimed.
  • Keep a mistake log: the question, why you missed it and the rule you'll use next time.
  • Use the on-screen tools you'll actually have: a calculator and two note boards, no scratch paper.
  • Take a full-length practice run at the same time of day as your appointment, with the two 15-minute breaks.
  • Don't skip Language Usage because it seems easy. At 45 seconds per question, it rewards speed you only get from practice.

Registration

Registration, Fees and Retakes

The ATDH costs $150, which includes score reports to the programs you choose when you apply. Apply 60 to 90 days before your test date, then book at Prometric once the ADA confirms your eligibility. These figures are from the 2026 ATDH Candidate Guide and the ADA application page.

ItemRule
Exam fee$150
Rescheduling fee$50 (30+ business days' notice), $70 (5–29 days), $125 (1–4 days)
Fee waiver50% partial waiver for eligible first-time testers with financial hardship, limited each year
Testing window6 months after your application is processed
RetakesWait 60 days between attempts; after 3 attempts, you need permission and can test once every 12 months
Score release3 to 4 weeks
IDTwo original, current IDs; the name must match your application exactly

The DAT uses the same DENTPIN and Prometric process, which our DAT registration guide walks through step by step. Your full testing history is reported to programs, and scores can't be canceled once you've started the test, so wait until your timed practice is where you want it.

Compare

ATDH vs DAT

The ATDH borrows the DAT's Perceptual Ability question types and its biology and general chemistry topics, but it's shorter and adds Language Usage. It has no organic chemistry and is scored 200 to 500 instead of the DAT's 200 to 600. If you're deciding between dentistry and dental hygiene, our OAT vs DAT comparison and DAT scoring guide explain how the DAT works.

Because the content overlaps, DAT prep tools work for the ATDH too; the Booster Prep section above covers the two marketed for the ATDH. For the full DAT courses, see our best DAT prep courses ranking and our DAT Booster vs DAT Bootcamp comparison.

FAQ

How long should I study for the ATDH?

Most students need 6 to 8 weeks at 10 to 12 hours a week if their biology and chemistry courses are recent. Plan on 10 to 12 weeks if you're returning to chemistry after a break or if Perceptual Ability is completely new to you.

What is a good ATDH score?

The ADA sets no passing score, and each program decides what it wants. The original scale was set so the average section score was about 350, so scores above 350 are above that starting average. Ask your target programs what scores their admitted students usually have.

Is there an ATDH practice test?

Yes. The ADA publishes a free set of 38 practice questions covering all six sections, with an answer key. It's useful for learning question formats, but the ADA says those questions aren't reviewed to live-exam standards, so don't treat your result as a score prediction.

Can I use a calculator on the ATDH?

Yes. The 2026 ATDH Candidate Guide says a digital calculator is provided on screen for Quantitative Reasoning and General Chemistry. You can't bring your own calculator. The Prometric test center gives you two note boards and two fine-tip markers instead of scratch paper and pencils.

What is the best ATDH prep course?

Booster. 56 of the 63 recent ATDH test takers in our focus group (89%) used it, and it's the one major company we found that markets courses for the ATDH. PATBooster ($49 a month) targets Perceptual Ability, and DATBooster ($549 for 90 days) adds biology, chemistry, reading and math. Pair either with the ADA's free materials.

How many times can I take the ATDH?

You can retake it after waiting 60 days, with a new application and fee each time. After three attempts, you must ask the ADA for permission to test again, and you're then limited to one attempt every 12 months. Programs see your full testing history.

Verdict

Final Verdict

The ATDH rewards steady, timed practice more than cramming. Start with the ADA's free practice questions to find your weak sections, review biology and general chemistry from a standard textbook, and drill Perceptual Ability every day, since it's the section with the most questions and the least time per question. Practice each section at its real pace from the first week, keep a mistake log, and finish with a full timed run that includes the breaks. Six to eight weeks is enough for most students with recent science courses. Confirm which of your programs require the ATDH before you pay the $150 fee.

How we reviewed

Sources