Arabic is the fastest-growing language in American households — and that’s leading the US Census Bureau to explore the tricky task of adjusting its questionnaires to ­accommodate the language’s right-to-left script.

The bureau is using focus groups to explore possible changes to the 2020 census questionnaires for Arabic speakers who are not English-proficient, the Pew Research Center reported Friday.

Arabic is now the seventh-most commonly spoken non-English language in US households. An estimated 1.1 million people ages 5 and older speak Arabic at home, an increase of 29 percent between 2010 and 2014.

The number who speak Spanish at home has grown only 6 percent during the same period.

Of those who speak Arabic at home, 38 percent are not proficient in English, according to census estimates.

That’s just below the 42 percent English proficiency rate among the 39.3 million US residents who speak Spanish at home.

The growth in Arabic is linked to continued immigration from Middle Eastern and North African countries, according to the Pew Research Center.

Possible changes to the census questionnaire include replacing the blocks for individual printed letters with a single open-field rectangle, so that answers can be written in connected Arabic script, the center said.

One major challenge facing census officials is whether to require a response in English and when to allow an Arabic response.

A focus-group study recommended that the address fields require people to use English, because an American address might not be accurately translated into Arabic, according to the Pew Research Center.

Arabic names present another complication — as they can be transliterated into English in different ways because the letters of the Arabic ­alphabet don’t necessarily have direct English equivalents.

For example, the Arabic name Hussein can be transliterated into English at least five additional ways: Hussain, Husein, Husain, Houssain and Houssein.