UltKit
Image11
Image ConverterCompress ImageResize ImageCrop ImageImage to PDFPassport Photo MakerImage to SVGAll Image tools →
PDF13
Compress PDFPDF ConverterPDF to ImageMerge PDFSplit PDFUnlock PDFProtect PDFAll PDF tools →
Documents & Data7
Convert to PDFDocument ConverterImage to Text (OCR)Image to ExcelData ConverterE-book ConverterAll Documents & Data tools →
Video6
Video ConverterCompress VideoVideo to AudioVideo to GIFTrim VideoAudio to VideoAll Video tools →
Audio4
Audio ConverterCompress AudioTrim AudioAudio to TextAll Audio tools →
More tools22
QR Code GeneratorZip FilesUnzip OnlineTime Zone ConverterUnit ConverterPassword GeneratorWord CounterColor PickerAll More tools →
BlogHow it works

PDF to Black and White

Black and white here means exactly two tones: every pixel ends up pure black or pure white, the way a fax machine or a photocopier on text mode sees a page. That is ideal for letters, forms and receipts, and harsh on anything with a photo in it.

PDF to Grayscale

or drop PDF files here ·

Max 95 MB per file· Up to 20 files· Deleted after 30 minutes

Color
128

Files are processed on our servers and deleted after 30 minutes.

How to use this tool

  1. 1

    Upload the PDF

    Add one PDF or up to 20, each up to 95 MB. Typed documents and scans both work.

  2. 2

    Check the threshold

    Convert to is already set to Black & white and Threshold to 128. Raise it if faint text disappears, lower it if the paper turns speckled.

  3. 3

    Convert and inspect

    Press Convert, zoom in on the lightest text in the result, and download.

Answer

How do I convert a PDF to pure black and white?

Upload it and press Convert. This page already sets Convert to Black & white with a Threshold of 128, so every pixel darker than mid-gray turns black and everything lighter turns white.

PDF to black and white: what true 1-bit means

A grayscale page keeps 256 shades from black to white. A black and white page, also called bilevel or 1-bit, keeps two. The Threshold decides which side each pixel falls on: its lightness is compared with the number you set, from 1 to 254, and there is no in-between. Typed text, line drawings, signatures and stamps come through crisp, often crisper than the scan, because pale paper and shadows simply vanish.

Two-tone pages are also what a fax line carries and what PDF has long had dedicated compression for: CCITT Group 4, from the fax world, and JBIG2, which arrived with PDF 1.4. That is why archives of typed documents and many government scan systems store pages as black and white rather than gray. If you are here to fix a color scan for a monochrome printer, make PDF black and white walks through that case.

tones per pixel: black or white
2
per pixel, against 8 for grayscale and 24 for color
1 bit
dpi of a Group 3 fax in fine mode
204 × 196
default threshold, the midpoint of the scale
128

Black and white PDF for fax and cheaper printing

Fax still matters in medicine, law and some government offices, and every Group 3 fax, the ITU-T T.4 standard behind ordinary fax machines, is bilevel. Standard mode samples a page at about 204 × 98 dpi and fine mode at 204 × 196 dpi, so small gray text is already marginal. A page you have converted and checked at the right threshold arrives looking the way you expect.

For printing, a pure black and white file means the printer lays down black toner only, and only where there is text or line. A color page printed in grayscale still covers backgrounds and photos with halftone dots, which uses toner across the whole area. For a full report with charts that must stay readable, grayscale PDF is the gentler choice; for a stack of typed pages, two tones are cheaper.

When black and white mode destroys photos

DoDon't
Typed letters, contracts and invoicesID cards and passport copies with a photo
Forms filled in with dark inkSlides with colored backgrounds or charts
Receipts and delivery notes for an expense systemMedical images, X-rays and photographs
Sheet music, line drawings and floor plansPages with pale pencil notes or highlighter

A photo has no right threshold

Thresholding turns a face into black blotches on white, because skin and shadows sit across the middle of the scale. If a page mixes text and a photo, set Convert to Text & graphics only, which leaves the photo untouched in color, or run that page through Grayscale instead.

PDF to black and white questions

Is a black and white PDF smaller than the color original?

For scanned pages, usually by a wide margin, since a two-tone image needs one bit per pixel instead of 24 and compresses with methods made for it. For a typed PDF with no images, the size barely changes, because text and lines were already tiny.

Should I convert a PDF to black and white before faxing it?

It helps. A Group 3 fax transmits only black and white, so the machine or online fax service makes that conversion anyway, with no way for you to preview it. Converting first lets you choose the threshold and check that stamps, signatures and light print survived.

What threshold works for a PDF with a gray background?

Lower it below the default, to around 100, so the gray paper falls on the white side. Then check the thinnest text strokes, which are the first thing a lower threshold removes.

Can I convert only the pages that are pure text to black and white?

Yes. Set Pages to Selected pages and list them, for example 1-3, 6. Run the photo pages through Grayscale separately if you need the whole document monochrome.

Does black and white mode affect hyperlinks and bookmarks?

Only colors change. Links still work and bookmarks stay in place; a blue link simply prints black, so it may no longer look clickable on paper.