Is AM Or PM Capitalized?

Is AM Or PM Capitalized? Capitalization. In running text, a.m. and p.m. are generally lowercased, with periods after each of the letters. But these abbreviations may also be capitalized—for example, in headings, signs, and notices. What is the correct way to write AM and PM? A.M. means “ante meridiem” and P.M. means for “post meridiem”,