Convert comics to EPUB
Whether it's a scanned golden-age book or a digital release, tanko turns a comic archive into a clean fixed-layout EPUB: every page resized for your reader's exact screen, contrast-corrected (aged, yellowed scans get their white background back), and packaged with proper cover and page order.
It runs entirely client-side — your files never touch a server, which also means no size limits and no waiting in line.
How to convert a comic to EPUB for any e-reader
- Start with a CBZ, CBR, or PDF. The format is detected from the file's first bytes, so mislabeled archives work; the picker only insists on one of the .cbz, .cbr, .zip, .rar, or .pdf extensions. One file at a time.
- Choose the reader you will use. Nine profiles cover current Kindles and Kobos from 1072x1448 up to 1860x2480. Pages are downscaled to the chosen panel and never upscaled.
- Set direction and spreads to match the book. Left to right for Western titles, right to left for manga; Auto spreads handles the usual case of a few double-page spreads in a portrait book.
- Download and load it. Kindles take the EPUB through Send to Kindle; Kobos take it over USB or a linked cloud folder; desktop and mobile reading apps open it as a fixed-layout book.
Scan cleanup: what the levels pass actually does
After a page is converted to grayscale, tanko builds a histogram and finds the brightness values at the 1st and 99th percentiles. Those become the new black and white points, so the yellow-gray of aged paper stretches to pure white and grayish ink to black, with the halftones in between spread proportionally.
Two kinds of pages are left alone. Pages whose 1st-to-99th range already covers 250 or more of the 255 available levels are clean and gain nothing; pages whose range is under 32 levels — an all-black endpaper, a fog panel, a solid color page — would only have their noise amplified. The decision is made per page, so a mixed archive gets mixed treatment.
The pass only runs for grayscale profiles; the Colorsoft and Libra Colour profiles keep the page as rendered. After it, a gamma of 1.8 darkens midtones and the page is dithered to 16 gray levels, in that order.
Downscaling large scans without losing line work
Archive scans are commonly 2,000 to 4,000 pixels wide, two to four times the panel. A single bilinear resample from that size drops most of the source pixels and aliases halftone dots into moire, so tanko halves the image repeatedly with high-quality smoothing until it is within 2x of the target, then does the final resample.
Aspect ratio is always kept. A page wider or narrower than the panel's proportions is fitted inside the panel bounds and the reader centers it, rather than stretching it to fill; the page XHTML declares the image's own pixel size as its viewport for exactly this reason.
Pages already smaller than the panel are left at their native size. Upscaling is off in the browser build because it cannot add detail and only inflates the file; a small page on a big panel is shown centered with a border.
Read the guide
- How to read CBR and CBZ comics on a Kindle · 8 min read
Frequently asked questions
- What input formats are supported?
- CBZ and CBR archives (plain ZIP and RAR too) with pages in JPEG, PNG, WebP, or GIF — plus PDF, rendered page-by-page. Format is detected from the file itself, so mislabeled archives still convert.
- What happens to old, yellowed scans?
- An automatic levels pass maps the aged paper tone back to clean white and faded ink to true black — without crushing the halftone shading in between. It skips pages that are already clean.
- What is the best format for comics on an e-reader?
- Fixed-layout EPUB: it carries page order, reading direction, page dimensions, and a cover in a form that Kindle (via Send to Kindle), Kobo, and reading apps all understand. CBZ and CBR are just archives, and PDF on e-ink means margins and no direction metadata.
- Does the converter crop borders or trim margins?
- No. Pages are resized and tone-corrected but never cropped, so scanned borders and PDF margins stay. Crop in an image tool or a PDF editor first if you need them gone.
- Can I convert a whole folder of comics at once?
- The browser converter handles one file per run. Drop the next file when the first finishes; each conversion runs in its own worker and the previous download link is replaced by the new one.
- Do my files get uploaded anywhere?
- No. Conversion runs entirely in your browser — the file never leaves your device. That's also why there are no size limits or queues.
- Is this really free?
- Yes. Single-file conversion with every device profile and every option is free, with no sign-up and no watermarks.