To earn a registered dietitian (RD) or registered dietitian nutritionist (RDN) credential—two names for the same credential—you must meet the criteria established by the Commission on Dietetic Registration (CDR), the credentialing agency for the Academy of Nutrition and Dietetics, and pass an exam. The exam may be referred to as the CDR exam, the RD exam or the Registration Examination for Dietitians.

To earn the RD credential, you must pass the exam sponsored by the CDR, which is the national credentialing agency for the Academy of Nutrition and Dietetics. The goal of the exam is to test applicants’ knowledge of nutrition and dietetics—a quality assurance measure of sorts. Passing the CDR exam and earning the national RD credential will qualify you for licensure or certification in most states so you may begin working. Requirements for state-issued license or certification for dieticians vary by state. 

Understanding the goal of the CDR exam may help you better grasp its importance and help you prepare for the test.

Before you register for the exam, make sure you meet the eligibility requirements for the CDR exam.

Currently, a bachelor’s degree is required to sit for the registration examination for dietitians by the Commission on Dietetic Registration, as well as a dietetic internship (DI). The degree must be accredited by the Accreditation Council for Education in Nutrition and Dietetics (ACEND). Starting Jan. 1, 2024, a graduate degree in a related field will be required to sit for the CDR exam, such as an ACEND-accredited Master of Science in Nutrition and Dietetics.

Those seeking knowledge in the dietetics and public health fields may pursue Master of Public Health (MPH) coordinated degree programs, namely MPH/RD programs. To learn more about eligibility requirements and internship options, explore our guide on how to become a registered dietitian. 

The CDR exam encompasses four content sections called domains. Each section in the CDR exam comprises a different percentage of the final grade, as outlined in the CDR’s test specifications online resource [PDF, 252 KB]:

The CDR exam is a computer-based adaptive test, a type of testing that is widely considered more efficient and accurate than paper-and-pencil tests. Your answers will determine which questions you receive next. 

The CDR exam handbook for candidates [PDF, 1.5 MB] can be found on the Commission on Dietetic Registration’s website. It contains information about the exam format, scheduling and more. The test is 2 1/2 hours and can be completed at a test center of your choice. There are 125 to 145 multiple-choice questions. Out of 125 questions, a student must answer 100 scored questions and 25 unscored pretest questions for the exam to be scored. Out of 145 questions, 120 scored questions and 25 unscored pretest questions must be answered. If fewer than 125 questions are answered when the testing period has ended, the student will fail the test. The exam questions are designed to test at either the comprehension or application level. 

An on-screen calculator is provided. 

When you are sure you meet the eligibility requirements and have been validated by CDR, you can take the CDR exam. You will be notified of your eligibility to schedule your exam via email by CDR’s testing vendor, Pearson VUE. The entire process, from the time CDR receives your eligibility information to the time you receive the Pearson VUE authorization to test email, takes three to four weeks.

Authorization expires after the test is taken or one year after receipt of the email, whichever occurs first. If you take the test and fail, you must contact CDR to re-establish eligibility to retake the test after 45 days. There is no limit on the number of times you may take the exam, provided you wait the required 45 days between test dates.

The RD exam is administered year-round at more than 250 locations in the United States. You may search for a test center near you on the Pearson Vue website. The fee to take the CDR exam is $200.

The rate of students who pass the CDR exam on their first try hovers around 70%. According to CDR data on group performance [PDF, 156 KB], out of the 1,692 first-time test-takers who took the exam from January through June 2020, 70% passed and 30% failed. For students who are repeating the exam, the CDR exam pass rates are reversed: In that same time period, out of 1,183 people who retook the exam, only 30% passed and 70% failed.

There is no one right way to prepare for the CDR exam. You know yourself best, and your study methods have gotten you this far already. That said, here are some tips you may find useful as you prepare for the exam:

The CDR exam may be challenging for some. Depending on the person, it can take several weeks or months of studying to fully prepare. Be sure to give yourself enough time, given your schedule and style of preparation.

Set a realistic study schedule and decide what topics you will study at which times. You may write it down in a paper planner or use Google calendar to map out study blocks. Decide whether you will study alone or with other people and where. Some people concentrate better away from home.

There are a number of free materials available online to help you prepare for the CDR exam, as well as paid print, online and audio materials. CDR publishes its own study guides and related materials for purchase. Other options include Inman Seminars’ print and audio review course for the RD exam and Mometrix Test Preparation study guides. To save costs, some students purchase used materials or share them with other students.

Note: CDR does not endorse any particular examination preparation program or offering. Purchasing a certification preparation product is not required and does not guarantee that an individual will pass the exam. 

Whether you use online testing tools, apps, flash cards or another method, practice may help you master the information.

Dietitians especially know the importance of eating a good breakfast the day of the exam. Also be sure to get a good night’s rest beforehand and leave yourself extra time to get to the exam location.   

In addition to those mentioned, there are a variety of resources to help you prepare for the exam. When deciding on which ones to use, consider your budget, timeframe and how you learn best. You may need a combination of tools to really grasp the information. Here are a few to consider: 

CDR exam handbook for candidates [PDF, 1.5 MB]. This free 11-page handbook from CDR contains general information about the exam, including getting authorization to test, scheduling the exam, payment, exam content, and interpreting score results.

Study Guide for the Registration Examination for Dietitians, 10th Ed. CDR publishes and sells this study guide, which includes tips and practice exams.

Registration Examinations for Dietitians 2017-21 Study Outline [PDF, 70 KB]. This 11-page free resource from CDR lists all the content domains and topics covered on the CDR exam. Students who have passed the exam recommend starting with the topics that are the most challenging to you.

EatRightPrep. The Academy of Nutrition and Dietetics offers this online RD exam prep tool. Purchase of a three-month subscription gives users access to several full-length practice exams with detailed performance reports after each exam and references for each question, as well as other study tools and tips. You can try it out with a free demo.

RD Exam Study Suite software. This multiple-choice study guide created by an RD, resembles the actual RD exam. It includes thousands of practice questions and videos. 

Pass the Exam Prep. This exam preparation guide teaches students the Study Smarter Method, a way of studying based on your learning style. The RD who created the Study Smarter Method claims this method is more efficient and effective than traditional studying methods, such as reading and highlighting information. Options include six-month online access or a spiral-bound book.

Now that you know what’s involved in preparing for the CDR exam and earning the RD credential, you may feel better prepared to take this next step toward a career as a dietitian. The CDR exam may be challenging, but don’t let that stop you from pursuing your goal to become an RD.

Last updated February 2021.