Reduce file size

Reduce file size… shrinks a PDF by recompressing its large images and clearing out unused data. Find it under File ▸ Reduce file size… or on the Pages toolbar menu. In the app: Help ▸ Show me.

Steps

1. Open the document and choose File ▸ Reduce file size….
2. Choose a preset. The estimate under Reduced size updates after each choice.

3. Compare Current size with Reduced size. The line below shows how many images were recompressed and how many were left as they are.
4. Click Save as… and choose a name. The default is the original name with -reduced added.

What changes

• Large photographic images (RGB or grey JPEG, or plain Flate-compressed) are scaled down and re-encoded as JPEG. An image is replaced only if it becomes at least 5% smaller, and images under 16 KB are left alone.
• Objects that nothing refers to are removed, and the file is saved with object streams.
• Text, vector graphics and page layout are not touched.
• Images with transparency masks, CMYK or indexed colour, and JBIG2, CCITT or JPEG 2000 images are left unchanged.

The open document is never altered. The reduced copy is a new file.

When it is refused

• Signed documents: a message says the document is digitally signed. Rewriting the file would invalidate the signature, so the command is not available.
• Encrypted (read-only) documents: "This document is encrypted: it cannot be rewritten."
• No gain: if a preset does not make the file smaller, Save as… reports "This setting does not make the file smaller. Try a smaller preset."

Related: Save and print, Recognize text (OCR).