1Upload the JPG images you want resized — work from the largest original you have rather than from a copy you already shrank once.
2Type a target width, a target height or a percentage, and leave the aspect-ratio lock on unless you deliberately want stretching.
3Run the resize; every file in the batch is taken to the same target in a single pass.
4Download the resized JPG file, or the whole set together as one archive.
Resize JPG FAQ
What dimensions should I actually target?
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Match the slot it will live in. A full-width web hero rarely needs more than 1920 pixels wide, a content image 1200, a thumbnail 400, and doubling those numbers covers high-DPI screens. Anything beyond that is bytes nobody sees.
How does Resize JPG change the dimensions?
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Concretely, the image is resampled with a Lanczos filter and then re-encoded, which means a resize is also a re-compression — so do it once from the largest original you have rather than in stages. You give it a target width, a target height or a percentage, and it works from the original rather than from a previously resized copy.
Is there anything specific to JPG I should watch for?
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Yes — every save re-runs the quantiser, so repeatedly editing and resaving a JPG compounds generation loss even if you never lower the quality slider. Worth checking before you resize a file you will not be able to regenerate.
What is the most common mistake when resizing JPG images?
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Upscaling. Enlarging cannot invent detail that was never captured, so the result is a soft version of the original at a bigger size. Always resize down from the largest source you have, and resize once rather than in stages.
What can I upload to Resize JPG?
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Anything in the lossy raster family — JPG, JPEG, JFIF and WebP — plus the lossless formats (PNG, BMP, TIFF) if you want to mix them in one batch. The format is read from the file header, not the extension, so a photo saved with the wrong suffix still goes through.
Is there a file size limit on Resize JPG?
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Yes: free accounts process images up to 25 MB each, which covers essentially every camera JPG and phone photo; the work is done by libjpeg-turbo and libwebp, the same libraries a desktop editor links against. Larger files are the one thing the free tier will stop you on, and the limit is per file rather than per batch.
Will Resize JPG lower the quality of my JPG images?
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A lossy source is already the result of one quantisation pass, and any operation that has to re-encode adds a second. Where the job can be done without touching the pixel data we do that instead, and where it cannot you choose the quality factor yourself rather than getting a fixed default.
Can I run Resize JPG on several JPG images at once?
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Yes. Drop the whole set into the upload area and they queue in parallel with identical settings — that is the main reason to do this in a browser rather than one file at a time in an editor. Free accounts run one file per batch; a pass lifts that.
Why does a EPUB site host Resize JPG?
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EPUB.to is built around the open eBook format — XHTML in a zip, reflowable by design, and readable on hardware nobody has thought about the layout for. A book is a zip full of markup, images and fonts, so almost every job people bring to an eBook site is really a job on one of those things. Resize JPG runs on the same upload and the same account as the conversions because that is where it is needed.
What should I do with the result once Resize JPG is finished?
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The converter on this site moves books between EPUB, MOBI, AZW3, PDF and DOCX, so a title ends up on whatever hardware is actually going to read it. Doing that after Resize JPG means the conversion is made from the version you settled on, not from the one you were still fixing.
Is Resize JPG here the same tool the sibling sites run?
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The engines are shared — the same toolchain, the same workers, the same limits. What a EPUB site adds is a view on reflow: which of these operations a reflowable book genuinely supports, and which ones only make sense on the fixed-layout media inside it. It also starts from one fact about the format this site is named after: the book is a zip of XHTML with a manifest, so the text costs almost nothing and every decision that matters is about the embedded images and font subsets.
Do I need an account, and does anything get kept?
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No account, and nothing is kept: uploads are deleted from the workers shortly after the job finishes, nothing is read and nothing is indexed. Free accounts exist for history and batch size, not for access.
