Donald Trump's use of vocabulary and grammar is more elementary than that of other candidates, according to a new study that compared the candidates' English language skills.

The New York businessman's grammar was comparable to a 5th grader's, lower than the average 6th to 8th grade levels used by Democratic Sens. Hillary Clinton and Bernie Sanders, as well as Republican Sens. Ted Cruz and Marco Rubio, according to a newly released Carnegie Mellon University's Language Technologies Institute study.

Sanders scored highest in vocabulary, and was ranked at the level of an 11th grader. Trump was most comparable to a 7th grader, while Clinton, Cruz and Rubio were all ranked between 9th and 10th grade.

"This analysis shows the changes that candidates make in the level of their speech according to the type of speech," wrote report analysts Elliot Schumacher and Maxine Eskenazi. "It also reflects each candidate's combination of personal delivery style and their analysis of the level of the audience they want to address."

Ohio Gov. John Kasich was not included in the survey, and Rubio has since suspended his campaign following a loss in Florida's primary Tuesday.

The in-depth analysis even compared this year's candidates to previous U.S. presidents. Abraham Lincoln and Ronald Reagan both boasted the highest cumulative speaking skills with averages hovering around a 10th grade level.

George W. Bush's grammar was rated worse than Trump's, ranked between 4th and 5th grade. But where Bush faltered in grammar, he made up for in vocabulary, which was at a 10th grade level.