What Duolingo score do you need for Webster University?

The test score table applies one set of minimums to undergraduate and graduate applicants. The page gives no Duolingo validity period or sending instructions.

Instead of a test, you can show English proficiency with at least one academic year of English-medium high school or college coursework at a regionally accredited US institution within the past two years (ESL coursework does not count).

For comparison, the same page sets IELTS at 6.0.

Academically qualified students who are not yet proficient may receive ESL-contingent acceptance and be placed into ESL courses. Completing ELS Language Center's English for Academic Purposes or Level 112, or the University of Central Florida CMMS Intensive English Program, also meets the requirement.

Requirements vary by programme and change between admissions cycles. The score that binds you is the one on your Webster programme page and in your offer letter, so check it there before you book a test.