{"id":771,"date":"2026-06-22T09:13:00","date_gmt":"2026-06-22T13:13:00","guid":{"rendered":"https:\/\/www.xconvert.com\/blog\/?p=771"},"modified":"2026-06-18T20:27:50","modified_gmt":"2026-06-19T00:27:50","slug":"why-is-my-scanned-pdf-so-big","status":"publish","type":"post","link":"https:\/\/www.xconvert.com\/blog\/why-is-my-scanned-pdf-so-big","title":{"rendered":"Why Is My Scanned PDF So Big? Causes and How to Shrink It"},"content":{"rendered":"\n<p class=\"wp-block-paragraph\">You scanned a five-page contract and ended up with a 40 MB PDF that bounces off your email provider\u2019s attachment limit. The text would fit in a few kilobytes \u2014 but a scanned page isn\u2019t text. It\u2019s a photograph of a page, and a scanner that\u2019s set to capture every fiber of the paper produces a photograph that\u2019s huge. The size comes from four settings working together: the resolution (DPI) the scan was captured at, the color mode (color, grayscale, or black-and-white), whether the scanner applied any image compression, and whether the resolution was downsampled before saving. This guide explains how each one drives the byte count, how they multiply, and how to shrink an already-bloated scan.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><strong>Quick answer:<\/strong> A scanned PDF is big because each page is a full-resolution <strong>image<\/strong>, not text. File size is driven by <strong>pixel count \u00d7 bit depth<\/strong>, so it scales with the <em>square<\/em> of the DPI (doubling DPI roughly quadruples size) and with the color mode: <strong>24-bit color<\/strong> is about <strong>3\u00d7 grayscale<\/strong>, and <strong>8-bit grayscale<\/strong> is about <strong>8\u00d7 1-bit black-and-white<\/strong>. A 600-DPI color scan with weak or no image compression is the worst case. To shrink one, re-compress and downsample it with a tool like <a href=\"https:\/\/www.xconvert.com\/compress-pdf\">xconvert\u2019s PDF Compressor<\/a> \u2014 pick the <strong>Screen<\/strong> or <strong>Ebook<\/strong> preset for the biggest reduction.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Jump to a section<\/h2>\n\n\n\n<ul class=\"wp-block-list\"><li><a href=\"#image-not-text\">Why a scanned page is an image, not text<\/a><\/li><li><a href=\"#dpi\">DPI: the squared term that dominates everything<\/a><\/li><li><a href=\"#color-mode\">Color vs grayscale vs black-and-white<\/a><\/li><li><a href=\"#compression\">Compression: the difference between 40 MB and 2 MB<\/a><\/li><li><a href=\"#downsampling\">Downsampling: shrinking the resolution that\u2019s already baked in<\/a><\/li><li><a href=\"#multiply\">How the four factors multiply: a worked diagnosis<\/a><\/li><li><a href=\"#shrink\">How to shrink a scanned PDF with xconvert<\/a><\/li><li><a href=\"#faq\">FAQ<\/a><\/li><\/ul>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"image-not-text\">Why a scanned page is an image, not text<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">A PDF you type or export from a word processor stores text as characters plus font instructions. The whole page might be a few kilobytes regardless of how much text it holds, because the reader draws the letters from the font.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">A <em>scanned<\/em> PDF is different. The scanner takes a picture of the physical page and embeds that picture \u2014 one raster image per page \u2014 inside the PDF wrapper. The PDF is really a folder of photographs with a thin container around them. Nothing in that file \u201cknows\u201d the page contains the word <em>contract<\/em>; it only knows the color of several million pixels. (Optical character recognition, or OCR, can add an invisible searchable text layer on top, but it does not remove the underlying image \u2014 the image is still what makes the file big.)<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">So the question \u201cwhy is my scanned PDF so big?\u201d is really \u201cwhy is this image so big?\u201d \u2014 and the answer is the standard formula for an uncompressed raster image:<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Every setting that shrinks a scan works by reducing one of those terms: fewer pixels (lower DPI or downsampling), fewer bits per pixel (a simpler color mode), or by compressing the result so the stored bytes are far fewer than the raw formula predicts. Adobe\u2019s documentation describes scanned pages in exactly these terms \u2014 resolution, color mode, and compression are the three knobs its scan settings expose (<a href=\"https:\/\/helpx.adobe.com\/acrobat\/desktop\/create-documents\/scan-documents-to-pdfs\/scanned-pdf-settings.html\">Adobe Acrobat \u2014 Scanned PDF settings<\/a>).<\/p>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"dpi\">DPI: the squared term that dominates everything<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">DPI (dots per inch \u2014 sometimes labeled PPI, pixels per inch, for the image itself) sets how many pixels the scanner captures per inch of paper. Because a page has two dimensions, DPI enters the size formula <em>twice<\/em>: doubling the DPI doubles both the width and the height in pixels, so it roughly <strong>quadruples<\/strong> the pixel count and therefore the raw size.<\/p>\n\n\n\n<figure class=\"wp-block-table\"><table><thead><tr><th>Scan DPI<\/th><th>Approx. pixels for a US Letter page (8.5 \u00d7 11 in)<\/th><th>Relative raw size<\/th><\/tr><\/thead><tbody><tr><td>150 DPI<\/td><td>~1,275 \u00d7 1,650<\/td><td>1\u00d7 (baseline)<\/td><\/tr><tr><td>300 DPI<\/td><td>~2,550 \u00d7 3,300<\/td><td>~4\u00d7<\/td><\/tr><tr><td>600 DPI<\/td><td>~5,100 \u00d7 6,600<\/td><td>~16\u00d7<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">A practical measurement bears this out: in one vendor\u2019s test, the same document grew from about 2.7 MB at 100 DPI to roughly 11 MB at 200 DPI, and a 600-DPI capture reached nearly 99 MB \u2014 about 4\u00d7 per DPI doubling (<a href=\"https:\/\/www.dynamsoft.com\/codepool\/size-optimization-of-scanned-document.html\">Dynamsoft \u2014 Size optimization of scanned documents<\/a>).<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">The trap is that <strong>higher DPI is rarely necessary for documents<\/strong>. For ordinary text pages, archival and records-management guidance and Adobe both point to <strong>300 DPI<\/strong> as the sweet spot \u2014 enough for clean reading and reliable OCR, without the size penalty of going higher. Adobe notes that for text recognition, 72 DPI is the floor and <strong>input above 600 DPI is downsampled anyway<\/strong>, and that \u201cfor most pages, black-and-white scanning at 300 DPI\u201d gives text best suited to recognition (<a href=\"https:\/\/helpx.adobe.com\/acrobat\/desktop\/create-documents\/scan-documents-to-pdfs\/scanned-pdf-settings.html\">Adobe Acrobat \u2014 Scanned PDF settings<\/a>). 600 DPI is meant for fine detail like photographs or fragile originals, not a printed memo. If your scanner shipped set to 600 DPI color \u201cfor quality,\u201d that single default is often the biggest reason your files are huge.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"color-mode\">Color vs grayscale vs black-and-white<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">The other multiplier in the formula is <strong>bit depth<\/strong> \u2014 how many bits each pixel uses to record its shade. Scanners typically offer three modes:<\/p>\n\n\n\n<figure class=\"wp-block-table\"><table><thead><tr><th>Color mode<\/th><th>Bits per pixel<\/th><th>What it stores<\/th><th>Relative size<\/th><\/tr><\/thead><tbody><tr><td>Black-and-white (bi-tonal)<\/td><td>1<\/td><td>Each pixel is purely black or white<\/td><td>1\u00d7 (smallest)<\/td><\/tr><tr><td>Grayscale<\/td><td>8<\/td><td>256 shades of gray<\/td><td>~8\u00d7 the B&amp;W size<\/td><\/tr><tr><td>Color (RGB)<\/td><td>24<\/td><td>~16.7 million colors (8 bits each for R, G, B)<\/td><td>~3\u00d7 the grayscale size<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">These ratios fall straight out of the bit-depth column (8 \u00f7 1 = 8; 24 \u00f7 8 = 3) and are confirmed by direct measurement \u2014 in Dynamsoft\u2019s test the same page measured roughly 1.1 MB at 1-bit, 8.7 MB at 8-bit grayscale, and 26.2 MB at 24-bit color before compression (<a href=\"https:\/\/www.dynamsoft.com\/codepool\/size-optimization-of-scanned-document.html\">Dynamsoft \u2014 Size optimization of scanned documents<\/a>).<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">The lesson: <strong>match the mode to the content.<\/strong> A page of black text on white paper carries no color or gray information worth keeping, so 1-bit black-and-white is both the smallest and a perfectly faithful representation. Scanning that same page in 24-bit color stores ~24\u00d7 the raw data to record millions of colors that aren\u2019t there. Reserve grayscale for pages with shading, signatures, or photographs in gray, and reserve full color for pages where the color genuinely matters (charts, photos, colored stamps). Many \u201cwhy is this 40 MB\u201d scans are plain text pages captured in color out of habit.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"compression\">Compression: the difference between 40 MB and 2 MB<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">The raw byte counts above are <em>before<\/em> compression. Whether your scanner applied compression \u2014 and which kind \u2014 often matters more than DPI or color mode, because the right compression can shrink a page by 90% or more.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">The catch is that some scanners and \u201csave as PDF\u201d paths embed each page as a lightly compressed or barely compressed image, so the file lands close to the raw size. That\u2019s the classic bloated scan: one large image per page, no meaningful image compression. Adobe\u2019s scan pipeline, by contrast, picks a compression scheme suited to the content (<a href=\"https:\/\/helpx.adobe.com\/acrobat\/desktop\/create-documents\/scan-documents-to-pdfs\/scanned-pdf-settings.html\">Adobe Acrobat \u2014 Scanned PDF settings<\/a>):<\/p>\n\n\n\n<figure class=\"wp-block-table\"><table><thead><tr><th>Content type<\/th><th>Compression Adobe recommends<\/th><th>Why<\/th><\/tr><\/thead><tbody><tr><td>Color or grayscale pages<\/td><td>JPEG2000, JPEG, or ZIP<\/td><td>Lossy\/lossless schemes built for continuous-tone images<\/td><\/tr><tr><td>Black-and-white \/ monotone pages<\/td><td>CCITT Group 4 (or JBIG2)<\/td><td>Designed specifically for bi-tonal text and line art<\/td><\/tr><tr><td>Mixed pages<\/td><td>Adaptive Compression<\/td><td>Splits the page into B&amp;W, gray, and color regions and compresses each with the best scheme<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">Compression is also where the modes compound: a black-and-white page compressed with CCITT Group 4 is tiny both because it\u2019s 1-bit <em>and<\/em> because text and line art compress extremely well. A color photo can\u2019t use CCITT and won\u2019t compress nearly as far without visible loss. So \u201cuse black-and-white for text\u201d helps twice \u2014 smaller raw data and far more effective compression.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">If your existing PDF is huge, it almost certainly has weak or no image compression baked in. You don\u2019t need to re-scan; you can re-compress it, which is what the <a href=\"https:\/\/www.xconvert.com\/compress-pdf\">PDF Compressor<\/a> does.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"downsampling\">Downsampling: shrinking the resolution that\u2019s already baked in<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">What if the scan already exists at 600 DPI color and you can\u2019t re-scan? <strong>Downsampling<\/strong> lowers the resolution of the embedded images after the fact by combining neighboring pixels into one \u2014 for example, turning a 600-DPI image into a 150-DPI one. Because resolution is the squared term, dropping from 600 to 150 DPI cuts the pixel count to roughly 1\/16.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Adobe\u2019s optimizer exposes several downsampling methods (average downsampling, subsampling, and bicubic downsampling) that trade speed against smoothness (<a href=\"https:\/\/helpx.adobe.com\/acrobat\/desktop\/create-documents\/scan-documents-to-pdfs\/scanned-pdf-settings.html\">Adobe Acrobat \u2014 Scanned PDF settings<\/a>). A compression tool typically pairs downsampling with re-encoding: it downsamples the page images to a sensible screen or print resolution, then re-compresses them. The combination is what turns a 40 MB scan into a few megabytes. Downsampling is lossy \u2014 you can\u2019t recover the discarded pixels \u2014 so keep the original if you might later need the full-resolution archival version.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"multiply\">How the four factors multiply: a worked diagnosis<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">The factors don\u2019t add up \u2014 they multiply, which is why bloated scans get so extreme. Walk a problem file through them:<\/p>\n\n\n\n<figure class=\"wp-block-table\"><table><thead><tr><th>Factor<\/th><th>\u201cBloated\u201d setting<\/th><th>\u201cLean\u201d setting<\/th><th>Approx. effect of fixing it<\/th><\/tr><\/thead><tbody><tr><td>DPI<\/td><td>600 DPI<\/td><td>300 DPI<\/td><td>~4\u00d7 smaller (squared term)<\/td><\/tr><tr><td>Color mode<\/td><td>24-bit color<\/td><td>1-bit B&amp;W (text) or 8-bit gray<\/td><td>up to ~24\u00d7 \/ ~3\u00d7 smaller<\/td><\/tr><tr><td>Compression<\/td><td>weak \/ none<\/td><td>JPEG2000, CCITT G4, or adaptive<\/td><td>often &gt;10\u00d7 smaller<\/td><\/tr><tr><td>Downsampling<\/td><td>none<\/td><td>downsampled to target DPI<\/td><td>folds into the DPI saving<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">A text-only page scanned at <strong>600 DPI, 24-bit color, lightly compressed<\/strong> can be tens of megabytes. The same page at <strong>300 DPI, 1-bit black-and-white, CCITT Group 4<\/strong> can be a few hundred kilobytes \u2014 a reduction well over 90% with no loss of legibility. Multiple sources put the combined saving from dropping to 300 DPI and a simpler color mode at \u201cover 90%\u201d for text-heavy documents (<a href=\"https:\/\/www.dynamsoft.com\/codepool\/size-optimization-of-scanned-document.html\">Dynamsoft \u2014 Size optimization of scanned documents<\/a>). That stacking is also why there\u2019s no single number to blame: it\u2019s usually all four at once.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"shrink\">How to shrink a scanned PDF with xconvert<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">If re-scanning isn\u2019t an option, re-compress the PDF you already have. xconvert\u2019s <a href=\"https:\/\/www.xconvert.com\/compress-pdf\">PDF Compressor<\/a> downsamples the embedded page images and re-encodes them, which targets exactly the bloat described above. Your file is uploaded over an encrypted connection, processed on our servers, and deleted automatically a few hours later \u2014 there\u2019s no account or watermark.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">The tool offers five presets, from smallest file to highest fidelity, plus an image-quality slider:<\/p>\n\n\n\n<figure class=\"wp-block-table\"><table><thead><tr><th>Preset<\/th><th>Best for<\/th><\/tr><\/thead><tbody><tr><td><strong>Screen (Best)<\/strong><\/td><td>Smallest file \u2014 on-screen viewing and email; most aggressive downsampling<\/td><\/tr><tr><td><strong>Ebook<\/strong><\/td><td>Balanced \u2014 readable on devices at a small size<\/td><\/tr><tr><td><strong>Default<\/strong><\/td><td>General-purpose compression<\/td><\/tr><tr><td><strong>Printer<\/strong><\/td><td>Office printing quality<\/td><\/tr><tr><td><strong>Prepress<\/strong><\/td><td>Commercial print workflows; least compression<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">How to use it:<\/p>\n\n\n\n<ol class=\"wp-block-list\"><li>Open the <a href=\"https:\/\/www.xconvert.com\/compress-pdf\">PDF Compressor<\/a> and choose <strong>Upload<\/strong> to add your scanned PDF.<\/li><li>Pick a preset \u2014 start with <strong>Screen<\/strong> or <strong>Ebook<\/strong> for the biggest reduction on an email-bound scan; choose <strong>Printer<\/strong> or <strong>Prepress<\/strong> if you still need to print it cleanly.<\/li><li>Adjust the image-quality slider if you want finer control over the size-versus-clarity trade-off.<\/li><li>Click <strong>Compress<\/strong> and download the smaller PDF.<\/li><\/ol>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"2560\" height=\"2000\" src=\"https:\/\/www.xconvert.com\/blog\/wp-content\/uploads\/2026\/06\/step-01-control-5.png\" alt=\"The xconvert PDF compressor with a scanned PDF loaded and the 'Ebook' downsampling preset selected\" class=\"wp-image-864\" srcset=\"https:\/\/www.xconvert.com\/blog\/wp-content\/uploads\/2026\/06\/step-01-control-5.png 2560w, https:\/\/www.xconvert.com\/blog\/wp-content\/uploads\/2026\/06\/step-01-control-5-300x234.png 300w, https:\/\/www.xconvert.com\/blog\/wp-content\/uploads\/2026\/06\/step-01-control-5-1024x800.png 1024w, https:\/\/www.xconvert.com\/blog\/wp-content\/uploads\/2026\/06\/step-01-control-5-768x600.png 768w, https:\/\/www.xconvert.com\/blog\/wp-content\/uploads\/2026\/06\/step-01-control-5-1536x1200.png 1536w, https:\/\/www.xconvert.com\/blog\/wp-content\/uploads\/2026\/06\/step-01-control-5-2048x1600.png 2048w\" sizes=\"auto, (max-width: 2560px) 100vw, 2560px\" \/><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">Two related tools help with the cases where compression alone isn\u2019t the goal:<\/p>\n\n\n\n<ul class=\"wp-block-list\"><li><strong><a href=\"https:\/\/www.xconvert.com\/convert-pdf-to-jpg\">Convert PDF to JPG<\/a><\/strong> \u2014 when you actually want the page images as separate JPGs (and you can choose a lower DPI, 72\u2013600, to control their size).<\/li><li><strong><a href=\"https:\/\/www.xconvert.com\/split-pdf\">Split PDF<\/a><\/strong> \u2014 when the file is large simply because it has many pages: split out only the pages you need to send instead of compressing the whole document.<\/li><\/ul>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"faq\">FAQ<\/h2>\n\n\n\n<h5 class=\"wp-block-heading\">Why is my scanned PDF so much bigger than a typed one?<\/h5>\n\n\n\n<p class=\"wp-block-paragraph\">Because a typed PDF stores text as characters drawn from a font, while a scanned PDF stores each page as a full raster image \u2014 a photograph of the page. The image\u2019s size depends on its pixel count and bit depth, not on how many words are on the page, so even a sparse page can be many megabytes.<\/p>\n\n\n\n<h5 class=\"wp-block-heading\">What DPI should I scan documents at?<\/h5>\n\n\n\n<p class=\"wp-block-paragraph\">For ordinary text documents, <strong>300 DPI<\/strong> is the widely recommended balance of legibility, reliable OCR, and reasonable size. Adobe notes that 72 DPI is the minimum for text recognition and that input above 600 DPI gets downsampled anyway. Reserve 600 DPI (or higher) for photographs, artwork, or fragile originals where fine detail matters (<a href=\"https:\/\/helpx.adobe.com\/acrobat\/desktop\/create-documents\/scan-documents-to-pdfs\/scanned-pdf-settings.html\">Adobe Acrobat \u2014 Scanned PDF settings<\/a>).<\/p>\n\n\n\n<h5 class=\"wp-block-heading\">Does scanning in black-and-white really make the file that much smaller?<\/h5>\n\n\n\n<p class=\"wp-block-paragraph\">Yes. Black-and-white (bi-tonal) stores 1 bit per pixel versus 8 for grayscale and 24 for color, so it\u2019s roughly <strong>8\u00d7 smaller than grayscale<\/strong> before compression \u2014 and it also compresses far more effectively with schemes like CCITT Group 4. For plain black text on white paper there\u2019s no color or gray detail to lose, so it\u2019s both smaller and faithful.<\/p>\n\n\n\n<h5 class=\"wp-block-heading\">Why does doubling the scan resolution more than double the file size?<\/h5>\n\n\n\n<p class=\"wp-block-paragraph\">Because resolution affects both the width and the height of the image. Doubling DPI doubles the pixels in each direction, so the total pixel count \u2014 and the raw size \u2014 goes up by about <strong>4\u00d7<\/strong>. That squared relationship is why a 600-DPI scan is roughly 16\u00d7 the raw size of a 150-DPI scan of the same page.<\/p>\n\n\n\n<h5 class=\"wp-block-heading\">Can I shrink a scanned PDF without re-scanning it?<\/h5>\n\n\n\n<p class=\"wp-block-paragraph\">Yes. A compression tool downsamples the embedded page images to a lower resolution and re-encodes them with efficient compression, which targets the same factors that made the file big. xconvert\u2019s <a href=\"https:\/\/www.xconvert.com\/compress-pdf\">PDF Compressor<\/a> does this; choose the <strong>Screen<\/strong> or <strong>Ebook<\/strong> preset for the largest reduction. Downsampling is lossy, so keep your original if you may need the full-resolution version later.<\/p>\n\n\n\n<h5 class=\"wp-block-heading\">Will compressing a scanned PDF ruin the text quality?<\/h5>\n\n\n\n<p class=\"wp-block-paragraph\">Compressing for screen or email may slightly soften the images, but at sensible settings the text stays clearly readable. Use the <strong>Printer<\/strong> or <strong>Prepress<\/strong> preset, or raise the image-quality slider, when you need to print the result. If the document must stay pristine, keep the original and compress only the copy you\u2019re sending.<\/p>\n\n\n\n<h5 class=\"wp-block-heading\">My scanned PDF is large because it has lots of pages \u2014 should I still compress it?<\/h5>\n\n\n\n<p class=\"wp-block-paragraph\">Compression still helps per page, but if the real problem is page count and you only need to send a few pages, it\u2019s often simpler to extract them. Use <a href=\"https:\/\/www.xconvert.com\/split-pdf\">Split PDF<\/a> to pull out just the pages you need, then compress that smaller file if necessary.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">Sources<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\"><em>Last verified 2026-06-18.<\/em><\/p>\n\n\n\n<ul class=\"wp-block-list\"><li><a href=\"https:\/\/helpx.adobe.com\/acrobat\/desktop\/create-documents\/scan-documents-to-pdfs\/scanned-pdf-settings.html\">Adobe Acrobat \u2014 Scanned PDF settings<\/a> \u2014 color\/grayscale vs black-and-white compression (JPEG2000, JPEG, ZIP, CCITT Group 4), Adaptive Compression, downsampling methods, and the 300-DPI \/ &gt;600-DPI-downsampled recommendations for text.<\/li><li><a href=\"https:\/\/www.dynamsoft.com\/codepool\/size-optimization-of-scanned-document.html\">Dynamsoft \u2014 Size optimization of scanned documents<\/a> \u2014 the <code>width \u00d7 height \u00d7 bit depth \u00f7 8<\/code> size formula, the DPI-doubling \u2248 4\u00d7 measurements, the 1-bit \/ 8-bit \/ 24-bit size comparison, and the \u201c&gt;90% reduction\u201d figure for dropping to 300 DPI and a simpler color mode.<\/li><\/ul>\n","protected":false},"excerpt":{"rendered":"<p>Scanned PDFs are big because each page is an image: high DPI, color mode, and weak compression multiply. Here&#8217;s how to diagnose and shrink one.<\/p>\n","protected":false},"author":3,"featured_media":857,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[5,14],"tags":[],"class_list":["post-771","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-how-to-guides","category-tools"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v27.8 - https:\/\/yoast.com\/product\/yoast-seo-wordpress\/ -->\n<title>Why Is My Scanned PDF So Big? Causes and How to Shrink It<\/title>\n<meta name=\"description\" content=\"Scanned PDFs are big because each page is an image: high DPI, color mode, and weak compression multiply. 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