How to remove blank pages from a scanned PDF

Where the blank pages come from

A duplex scanner captures both sides of every sheet, because it has no way of knowing that the backs are empty. Feed it thirty single-sided pages and it faithfully produces sixty images.

Some scanner software offers blank-page detection, but it is often off by default, and its threshold is frequently either too aggressive — dropping pages that carry a faint stamp — or too timid, letting every speckled back-side through.

The blanks are not truly empty either. They are full-resolution images of a white page, complete with the faint speckle every scanner produces, the shadow of the sheet's edge, and sometimes a ghost of the text printed on the other side. That is why they add real weight to the file rather than being free.

Removing them

The preview is the important part. You see the decision before it is made, so a page holding one faint line is never removed without you noticing. If something is flagged that should not be, change the sensitivity and look again.

1. 1Open the Delete blank pages tool and select your scanned PDF.
2. 2Choose how empty a page must be to count as blank. Balanced ignores scanner speckle and is right for most scans.
3. 3Check the preview — every page that will be deleted is marked — then confirm and download.

How the detection actually works

Each page is rendered to a small image and the tool measures what proportion of its pixels are dark enough to count as ink. A page that is 0.0004 ink is almost certainly a blank sheet with scanner noise on it. A page that is 0.03 ink is a page with a sentence on it.

The sensitivity setting is simply where that threshold sits. This is worth understanding because it explains the tool's one blind spot: it measures how much ink is on the page, not what the ink says. A page containing nothing but a page number carries very little ink, and a page containing a single large photograph of a white wall carries very little too.

That is exactly why the preview exists. The measurement is mechanical; the judgement is yours.

Choosing the right sensitivity

If you are unsure, start with Balanced and read the preview. Moving to Aggressive is a decision to discard pages that do contain something, so make it deliberately.

What this does to file size

Removing half the pages of a scan usually removes close to half its size, since each blank was a full-page image. It is common for this single step to do more for a bloated scan than compression does — and unlike compression, it is completely lossless for the pages you keep.

The best results come from doing both, in this order: delete the blanks first, then compress what remains. Compressing sixty pages and then deleting thirty of them means half your processing time was spent optimising pages you were about to throw away.

Preventing them at the scanner

If this is a recurring problem, the fix upstream is worth five minutes. Most scanner drivers have a simplex or single-sided mode — use it for single-sided originals rather than scanning duplex and cleaning up afterwards.

Where your driver has its own blank-page detection, test it on a stack you can check, since default thresholds vary widely between manufacturers. And if you are scanning mixed stacks where some sheets are printed on both sides, duplex plus this tool is genuinely the more reliable route.

When you should not remove them

Some blank pages are deliberate. Legal contracts, court filings, tender submissions and printed books often carry pages marked "this page intentionally left blank" precisely so that nobody can claim a page went missing — and removing them can break the pagination the document refers to.

The same applies to anything that has been paginated for an official process. If the covering letter says "see page 47" and you have removed six blanks, page 47 is now something else entirely.

For those documents, use Strict, read the preview carefully, and when in doubt keep the page. An unnecessary blank costs you a few hundred kilobytes; a missing page in a legal bundle costs considerably more.