PDF goes from 38 MB to 2.5 GB when converted to Epub?

vuther316 · Yesterday, 11:26 PM

Hi
I was trying to convert a book from a PDF to Epub so I could upload it to the kindle app, but when I converted it it ballooned up to 2.5 GB, which is far above the limit for send to kindle, or the email version of it to send it to my kindle library.
Any ideas why or what can be done to resolve this?
Please see the attached image of one of the pages (they are all images of scanned pages in the PDF),

Click image for larger version

Name: 2b736126d975f4cf6e108280fe037c8c.jpg
Views: 9
Size: 1.01 MB
ID: 219783

and the log from the conversion

Spoiler:

kovidgoyal · Yesterday, 11:28 PM

Presumably this is a scan pdf i.e. all the pages are images. It will be because in EPUB the images are stored in a less space efficient format (EPUB and PDF dont support the same set of image formats). Open the EPUB in the edit book tool and see for yourself.

tomsem · Today, 03:26 AM

Check the page size of the PDF pages.

These should be exactly the same as the physical copy. You will need some PDF editor to change them, or maybe some command line tool can do this. I sometimes discover page size is huge, like 32in x 24in, and conversion can expand whatever the pixel resolution to match. The PDF image objects themselves do not have PPI property, and scale according to the page dimensions.

Kindle Create, for example, can import PDF as image container for comic format. It exhibits exactly this bloating behavior.

rantanplan · Today, 06:16 AM

You can also just upload the pdf itself.

Yesterday, 11:26 PM	#1
vuther316 Junior Member Posts: 2 Karma: 10 Join Date: Dec 2025 Device: Kindle App (Mostly on a Samsung Galaxy Smartphone)	PDF goes from 38 MB to 2.5 GB when converted to Epub? Hi I was trying to convert a book from a PDF to Epub so I could upload it to the kindle app, but when I converted it it ballooned up to 2.5 GB, which is far above the limit for send to kindle, or the email version of it to send it to my kindle library. Any ideas why or what can be done to resolve this? Please see the attached image of one of the pages (they are all images of scanned pages in the PDF), and the log from the conversion Spoiler: Convert book 1 of 1 (The complete sagas of Icelanders, including 49 tales) Conversion options changed from defaults: cover: 'C:\\Users\\vuther316\\AppData\\Local\\Temp\\calib re-0xv_ea_s\\zu0b29ac.jpeg' read_metadata_from_opf: 'C:\\Users\\vuther316\\AppData\\Local\\Temp\\calib re-0xv_ea_s\\z2i_8ztm.opf' verbose: 2 pdf_header_regex: None output_profile: 'generic_eink' pdf_footer_regex: None Resolved conversion options calibre version: 8.16.2 {'add_alt_text_to_img': False, 'asciiize': False, 'author_sort': None, 'authors': None, 'base_font_size': 0.0, 'book_producer': None, 'change_justification': 'original', 'chapter': "//[((name()='h1' or name()='h2') and re:test(., " "'\\s((chapter\|book\|section\|part)\\s+)\|((prolog\|p rologue\|epilogue)(\\s+\|$))', " "'i')) or @class = 'chapter']", 'chapter_mark': 'pagebreak', 'comments': None, 'cover': 'C:\\Users\\vuther316\\AppData\\Local\\Temp\\calib re-0xv_ea_s\\zu0b29ac.jpeg', 'debug_pipeline': None, 'dehyphenate': True, 'delete_blank_paragraphs': True, 'disable_font_rescaling': False, 'dont_split_on_page_breaks': False, 'duplicate_links_in_toc': False, 'embed_all_fonts': False, 'embed_font_family': None, 'enable_heuristics': False, 'epub_flatten': False, 'epub_inline_toc': False, 'epub_max_image_size': 'none', 'epub_toc_at_end': False, 'epub_version': '2', 'expand_css': False, 'extra_css': None, 'extract_to': None, 'filter_css': '', 'fix_indents': True, 'flow_size': 260, 'font_size_mapping': None, 'format_scene_breaks': True, 'html_unwrap_factor': 0.4, 'input_encoding': None, 'input_profile': <calibre.customize.profiles.InputProfile object at 0x0000015F3F3A6ED0>, 'insert_blank_line': False, 'insert_blank_line_size': 0.5, 'insert_metadata': False, 'isbn': None, 'italicize_common_cases': True, 'keep_ligatures': False, 'language': None, 'level1_toc': None, 'level2_toc': None, 'level3_toc': None, 'line_height': 0.0, 'linearize_tables': False, 'margin_bottom': 5.0, 'margin_left': 5.0, 'margin_right': 5.0, 'margin_top': 5.0, 'markup_chapter_headings': True, 'max_toc_links': 50, 'minimum_line_height': 120.0, 'no_chapters_in_toc': False, 'no_default_epub_cover': False, 'no_images': False, 'no_inline_navbars': False, 'no_svg_cover': False, 'output_profile': <calibre.customize.profiles.GenericEink object at 0x0000015F3F3B2AD0>, 'page_breaks_before': "//[name()='h1' or name()='h2']", 'pdf_engine': 'calibre', 'pdf_footer_regex': None, 'pdf_footer_skip': -1, 'pdf_header_regex': None, 'pdf_header_skip': -1, 'prefer_metadata_cover': False, 'preserve_cover_aspect_ratio': False, 'pretty_print': True, 'pubdate': None, 'publisher': None, 'rating': None, 'read_metadata_from_opf': 'C:\\Users\\vuther316\\AppData\\Local\\Temp\\calib re-0xv_ea_s\\z2i_8ztm.opf', 'remove_fake_margins': True, 'remove_first_image': False, 'remove_paragraph_spacing': False, 'remove_paragraph_spacing_indent_size': 1.5, 'renumber_headings': True, 'replace_scene_breaks': '', 'search_replace': '[]', 'series': None, 'series_index': None, 'smarten_punctuation': False, 'sr1_replace': None, 'sr1_search': None, 'sr2_replace': None, 'sr2_search': None, 'sr3_replace': None, 'sr3_search': None, 'start_reading_at': None, 'subset_embedded_fonts': False, 'tags': None, 'timestamp': None, 'title': None, 'title_sort': None, 'toc_filter': None, 'toc_threshold': 6, 'toc_title': None, 'transform_css_rules': '[]', 'transform_html_rules': '[]', 'unsmarten_punctuation': False, 'unwrap_factor': 0.45, 'unwrap_lines': True, 'use_auto_toc': False, 'verbose': 2} InputFormatPlugin: PDF Input running on C:\Users\vuther316\AppData\Local\Temp\calibre-0xv_ea_s\lx7ksz5d.pdf Converting file to html... pdftohtml log: Page-1 Page-2 Page-3 Page-4 Page-5 Page-6 Page-7 Page-8 Page-9 Page-10 Page-11 Page-12 Page-13 Page-14 Page-15 Page-16 Page-17 Page-18 Page-19 Page-20 Page-21 Page-22 Page-23 Page-24 Page-25 Page-26 Page-27 Page-28 Page-29 Page-30 Page-31 Page-32 Page-33 Page-34 Page-35 Page-36 Page-37 Page-38 Page-39 Page-40 Page-41 Page-42 Page-43 Page-44 Page-45 Page-46 Page-47 Page-48 Page-49 Page-50 Page-51 Page-52 Page-53 Page-54 Page-55 Page-56 Page-57 Page-58 Page-59 Page-60 Page-61 Page-62 Page-63 Page-64 Page-65 Page-66 Page-67 Page-68 Page-69 Page-70 Page-71 Page-72 Page-73 Page-74 Page-75 Page-76 Page-77 Page-78 Page-79 Page-80 Page-81 Page-82 Page-83 Page-84 Page-85 Page-86 Page-87 Page-88 Page-89 Page-90 Page-91 Page-92 Page-93 Page-94 Page-95 Page-96 Page-97 Page-98 Page-99 Page-100 Page-101 Page-102 Page-103 Page-104 Page-105 Page-106 Page-107 Page-108 Page-109 Page-110 Page-111 Page-112 Page-113 Page-114 Page-115 Page-116 Page-117 Page-118 Page-119 Page-120 Page-121 Page-122 Page-123 Page-124 Page-125 Page-126 Page-127 Page-128 Page-129 Page-130 Page-131 Page-132 Page-133 Page-134 Page-135 Page-136 Page-137 Page-138 Page-139 Page-140 Page-141 Page-142 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Page-254 Page-255 Page-256 Page-257 Page-258 Page-259 Page-260 Page-261 Page-262 Page-263 Page-264 Page-265 Page-266 Page-267 Page-268 Page-269 Page-270 Page-271 Page-272 Page-273 Page-274 Page-275 Page-276 Page-277 Page-278 Page-279 Page-280 Page-281 Page-282 Page-283 Page-284 Page-285 Page-286 Page-287 Page-288 Page-289 Page-290 Page-291 Page-292 Page-293 Page-294 Page-295 Page-296 Page-297 Page-298 Page-299 Page-300 Page-301 Page-302 Page-303 Page-304 Page-305 Page-306 Page-307 Page-308 Page-309 Page-310 Page-311 Page-312 Page-313 Page-314 Page-315 Page-316 Page-317 Page-318 Page-319 Page-320 Page-321 Page-322 Page-323 Page-324 Page-325 Page-326 Page-327 Page-328 Page-329 Page-330 Page-331 Page-332 Page-333 Page-334 Page-335 Page-336 Page-337 Page-338 Page-339 Page-340 Page-341 Page-342 Page-343 Page-344 Page-345 Page-346 Page-347 Page-348 Page-349 Page-350 Page-351 Page-352 Page-353 Page-354 Page-355 Page-356 Page-357 Page-358 Page-359 Page-360 Page-361 Page-362 Page-363 Page-364 Page-365 Page-366 Page-367 Page-368 Page-369 Page-370 Page-371 Page-372 Page-373 Page-374 Page-375 Page-376 Page-377 Page-378 Page-379 Page-380 Page-381 Page-382 Page-383 Page-384 Page-385 Page-386 Page-387 Page-388 Page-389 Page-390 Page-391 Page-392 Page-393 Page-394 Page-395 Page-396 Page-397 Page-398 Page-399 Page-400 Page-401 Page-402 Page-403 Page-404 Page-405 Page-406 Page-407 Page-408 Page-409 Page-410 Page-411 Page-412 Page-413 Page-414 Page-415 Page-416 Page-417 Page-418 Page-419 Page-420 Page-421 Page-422 Page-423 Page-424 Page-425 Page-426 Page-427 Page-428 Page-429 Page-430 Page-431 Page-432 Page-433 Page-434 Page-435 Page-436 Page-437 Page-438 Page-439 Page-440 Page-441 Page-442 Page-443 Page-444 Page-445 Page-446 Page-447 Page-448 Page-449 Page-450 Page-451 Page-452 Page-453 Page-454 Page-455 Page-456 Page-457 Page-458 Page-459 Page-460 Page-461 Page-462 Page-463 Page-464 Retrieving document metadata... Generating manifest... Rendering manifest... Parsing all content... Parsing index.html ... Generating default TOC from spine... Merging user specified metadata... Detecting structure... Auto generated TOC with 0 entries. Flattening CSS and remapping font sizes... Source base font size is 12.00000pt Removing fake margins... Found 928 items of level: p_1 p_1 left margin stats: Counter({'0': 928}) p_1 right margin stats: Counter({'0': 928}) Cleaning up manifest... Trimming unused files from manifest... Trimming 'index.xml' from manifest Creating EPUB Output... Splitting markup on page breaks and flow limits, if any... Looking for large trees in index.html... No large trees found This EPUB file has no Table of Contents. Creating a default TOC EPUB output written to C:\Users\vuther316\AppData\Local\Temp\calibre-0xv_ea_s\5p61ksc8.epub Last edited by BetterRed; Today at 03:51 AM. Reason: SPOILER LOG files (@td) Thumbnail image (@BR)*

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Yesterday, 11:28 PM	#2
kovidgoyal creator of calibre Posts: 45,716 Karma: 28549306 Join Date: Oct 2006 Location: Mumbai, India Device: Various	Presumably this is a scan pdf i.e. all the pages are images. It will be because in EPUB the images are stored in a less space efficient format (EPUB and PDF dont support the same set of image formats). Open the EPUB in the edit book tool and see for yourself.

Today, 03:26 AM	#3
tomsem Grand Sorcerer Posts: 7,069 Karma: 28000001 Join Date: Apr 2009 Location: USA Device: iPhone 15PM, Kindle Scribe, iPad mini 6, PocketBook InkPad Color 3	Check the page size of the PDF pages. These should be exactly the same as the physical copy. You will need some PDF editor to change them, or maybe some command line tool can do this. I sometimes discover page size is huge, like 32in x 24in, and conversion can expand whatever the pixel resolution to match. The PDF image objects themselves do not have PPI property, and scale according to the page dimensions. Kindle Create, for example, can import PDF as image container for comic format. It exhibits exactly this bloating behavior.

Today, 06:16 AM	#4
rantanplan Weirdo Posts: 965 Karma: 12501486 Join Date: Nov 2019 Location: Wuppertal, Germany Device: Kobo Sage, Kobo Libra 2, Kindle Paperwhite 2021, Kindle Scribe 2022	You can also just upload the pdf itself.

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