Avery 5390 is the classic clip-holder name badge insert: 3-1/2 x 2-1/4 inches, eight per Letter sheet. Getting fifty names onto them is the part nobody warns you about.
Eight inserts per Letter sheet in two columns of four, with wide side margins. The badge sits landscape: 3.5 inches wide, 2.25 inches tall. Use the official Avery template for pre-cut sheets. The generator offers generic plain-paper grids only; alignment against Avery stock is not verified.
Printers have unprintable margins and slightly different paper paths. A template that is mathematically right can still print a millimeter off. The fix is boring: print one sheet on plain paper, hold it against the real insert sheet, and only then run the batch.
Word's mail merge can fill the grid from a spreadsheet, but it asks for the right template, the right data connection and a quiet afternoon. It works; it is just built for people who do it every week.
If your list is already in a spreadsheet, paste it into the generator, pick a generic cut-paper grid and download the PDF. For plain cut paper, no mail merge, and your list never leaves your browser.
The free generator makes 5 badge PDFs a day, with no signup and no upload.
Make cut-paper badges