Excel to PDF with (or without) gridlines — the setting that controls it

Short answer: Two different checkboxes both say “Gridlines” and only one affects the PDF. Page Layout → Sheet Options → Gridlines → Print decides whether the grid appears in the export. The View checkbox next to it only changes what you see on screen. The setting is per worksheet, not per workbook, so turning it on for the sheet you are looking at does nothing for the other twelve.

Turning them on

Select the worksheet (or Ctrl-click several tabs to do them together).
Page Layout → Sheet Options → Gridlines → tick Print.
Export. The grid renders as light lines around every cell in the print range.

Turning them off

Same checkbox, unticked. If lines still appear in the PDF, they are not gridlines — they are borders, applied as cell formatting, and no gridline setting will remove them. Select the range, then Home → Borders → No Border.

That distinction is behind most of the confusion. Gridlines are a display and print option; borders are formatting stored in the cell. A file that came from someone else usually has both.

The things that surprise people

Gridlines print only where there is a print range. Empty cells beyond the used range do not get a grid, so a sparse sheet can look half-lined.
Fill colours hide gridlines. A white fill counts as a fill. If a block of cells lost its grid, check for a fill rather than the setting.
The setting travels with the sheet, not the workbook. Copying a sheet copies its gridline setting; adding a new sheet gets the default (off for printing).
Gridlines are always thin and grey. They do not respond to line-weight settings. If you want heavier or coloured lines, you want borders.

Which one you actually want

For a data table someone will read on paper, borders usually beat gridlines: you can weight the header row, bound the totals, and leave the body light. Gridlines are the fast answer when you want every cell edge visible without formatting anything — a raw data dump, a check sheet, a working copy.

If you just need a clean PDF of a spreadsheet and would rather not set any of this by hand, the free web converter takes a single .xlsx, .xls, .xlsm or .csv in the browser and lays the sheet out for the page; it uploads your file, converts it and deletes it afterwards.

FAQ

Why do gridlines show on screen but not in the PDF? Because the View and Print checkboxes are separate. Tick Page Layout → Sheet Options → Gridlines → Print.

Why are gridlines still in my PDF after unticking the box? They are almost certainly borders rather than gridlines. Select the range and clear the borders with Home → Borders → No Border.

Can I set gridlines for the whole workbook at once? Not with one switch. Ctrl-click all the sheet tabs to group them, then set the checkbox once — it applies to every selected sheet. Ungroup afterwards so later edits do not hit all sheets.

Do gridlines affect where the page breaks fall? No. They are drawn inside the existing layout and change nothing about pagination.