Your PDF needs to rotate exactly 90 degrees — landscape charts that came out portrait, portrait pages that came out sideways. Not 180 (that's upside-down). Not 270 (that's three-quarter turn). Just 90.
Flint is one click per 90-degree turn.
Clockwise vs counter-clockwise
Open rotate PDF pages and you'll see two rotation buttons. Clockwise (CW) rotates 90° to the right — the top of the page moves to the right edge. Counter-clockwise (CCW) rotates 90° to the left — the top moves to the left edge. Click once for 90°. Click twice for 180°. Click three times for 270°.
Pick the direction by looking
Don't try to reason about degrees in the abstract. Look at the thumbnail. If the page reads 'sideways with the top to the right', click CCW to bring the top back up. If 'top to the left', click CW. The thumbnail updates immediately so you can see if you got it right.
Applying to specific pages only
Select the pages you want rotated (or 'select all'). Click your rotation. Save. Only selected pages rotate; the rest stay put.
Page dimensions after 90°
Width and height swap. A portrait A4 (210x297) becomes landscape A4 (297x210). Printers handle this fine if the paper matches. Onscreen viewers display correctly regardless.
FAQ
Why does my reader auto-rotate the wrong way?
Some readers ignore PDF rotation hints. Flint writes the rotation into the file so every standards-compliant reader displays it correctly.
Can I undo within Flint?
Yes. Rotate back the other direction. Or click 'reset' to revert all changes before saving.
Does 90° rotation degrade image quality?
No. Rotation is a metadata operation, not a re-render. Pixels are unchanged.
Does the file get bigger?
Negligible. Adds a few bytes per rotated page.
One click, ninety degrees, saved. Rotate 90°.