How can I reduce a scanned document's size without making the text unreadable?

Start with a small, reversible change rather than lowering every setting at once. If the scan is in color but the page only contains text or monochrome content, try grayscale. If the file is still too large, try a lower resolution and compare the saved result. Higher resolution captures more detail and produces a larger file; lowering it reduces both. Brother gives about 200 dpi as usually acceptable for text on two particular scanner models, but that is not a universal target for every scanner or document. [S1]

Keep the original scan, if available, until you have checked the smaller copy. That gives you a fallback if fine print, faint marks, or other details become hard to read.

Choose the least colorful mode that still preserves information you need. Grayscale uses less data per scanned dot than color, and black-and-white uses less than grayscale. But smaller files can come at the cost of detail, so compare the result rather than assuming the smallest option is best. [S1]

For a page with colored highlights, handwriting, stamps, or diagrams, check whether those distinctions remain visible after conversion. If color conveys meaning, retain color and try reducing resolution instead. One scanner-software workflow documented by Brother offers modes ranging from 24-bit color through gray options to black-and-white, but the available names and controls depend on the device and software. [S2]

Check whether the scan includes unnecessary blank space around the page. The scanned area affects file size, so framing the page more closely can help without changing the text itself. [S1]

Then look for a file-size or compression setting in your scanning app. Some workflows expose a File Size control for JPEG or PDF, but this is not available everywhere, and the menu may look different across operating systems. [S2] If you use such a control, make a copy or test scan first; do not assume a setting is safe just because it makes a much smaller file.

A practical sequence is: trim excess area, try grayscale if suitable, then adjust resolution or an available file-size control. Change one setting per test so you can tell what affected legibility.

Open the saved file—not just the scanner preview—and view it at ordinary reading size. Check a representative page, including the smallest print and any faint or important marks. Brother's guidance specifically calls for checking the saved scan at ordinary reading size after changing settings. [S2] If a page is unclear, restore the previous setting or use a less aggressive reduction and test again.

For example, suppose a text-only report is scanned in color and surrounded by wide blank margins. Make a copy, scan in grayscale with a closer page area, save it, and inspect the smallest text at normal reading size. If it is clear but the file is still too large, test a modest resolution change on another copy. This is a test sequence, not a guaranteed outcome: the sources do not establish one ideal resolution, compression level, or readability test for every document, scanner, and purpose.