Times, Arial, Helvetica-like stacks

Journal and conference guidelines still routinely demand Times for body text or Arial for figures, decades after those fonts stopped being anyone’s aesthetic first choice. In LaTeX there are two ways to satisfy such a requirement, and which one applies depends on your engine. Classic pdfLaTeX cannot load the actual Times New Roman or Arial files, so it uses metric-compatible clones shipped as packages. XeLaTeX and LuaLaTeX load the real system fonts through fontspec.

The package route

\usepackage{newtxtext,newtxmath} % Times-like
\usepackage{helvet}
\renewcommand{\familydefault}{\sfdefault}

newtxtext switches the text font to a Times clone, and newtxmath provides matching math. The pairing matters: changing only the text font leaves equations in the default Computer Modern, and the mismatch between a Times paragraph and Computer Modern math is immediately visible. newtx is the maintained successor to the old times and txfonts packages, which you should avoid in new documents, partly because the old stacks left math unconverted and partly because some produce the bitmap fonts described in blurry text in the PDF viewer.

helvet provides a Helvetica clone as the sans-serif family, which also stands in for Arial, since Arial was designed to match Helvetica’s metrics. Loading it does not change the document font, because body text uses the serif family. The \renewcommand{\familydefault}{\sfdefault} line performs that switch: \familydefault is the family LaTeX uses for ordinary text, and setting it to \sfdefault, the sans-serif family, makes the whole document Helvetica-like. Omit that line if you only need sans-serif headings or figure labels. If Helvetica runs slightly large next to your text font, \usepackage[scaled=0.92]{helvet} brings it in line.

The fontspec route

\usepackage{fontspec}
\setmainfont{Times New Roman}
\setsansfont{Arial}

Under XeLaTeX or LuaLaTeX, fontspec addresses fonts by name and loads them from the operating system, so this sets the genuine Times New Roman as the main (serif) family and genuine Arial as the sans family. The fonts must actually be installed on the machine, which is worth remembering when a document moves between computers or into CI; a font that travels with the project avoids the problem, as shown in a font file next to the project. Math is again a separate concern, handled by unicode-math or by keeping newtxmath alongside. The engine tradeoffs are covered in why people switch to XeLaTeX.

The practical rule

Before choosing either route, check whether the venue’s own class file already sets the fonts, because most do, and stacking your own font packages on top of a class that has spoken produces warnings at best. Add font packages only to documents whose class leaves the choice to you.