Image Compressor for KDP
Drop up to ten images and get them back under your byte target, as a zip. Runs in your browser; nothing is uploaded unless you ask for it.
Your images never leave this device. Every file is compressed here in your browser — no upload, no account, and no copy on our servers. The one exception is the Book Studio button, and only if you press it. If the page itself hits an error we send a report about the error — never your file.
A byte target, not a quality slider
Most compressors ask you to pick a quality number and then hope. That is the wrong way round when the requirement is a limit: what you know is “under 2 MB”, and what you want is the best picture that fits. So this searches for the highest quality that meets your cap, one file at a time, and tells you which quality it landed on.
It uses the same encoders the desktop tools do — mozjpeg for JPEG, libwebp for WebP — compiled to run in your browser. That is what makes the files genuinely smaller at the same quality rather than just smaller.
When compression is the wrong answer
If a file is over the cap because it is enormous in pixels, compressing it harder trades sharpness for a number. Resizing it is the better fix, and for A+ Content there is a tool on this site that resizes to the exact module dimensions. Compression is for a file that is the right size and simply too heavy.
Nothing here changes an image’s pixel dimensions, and nothing here adds detail. A file that prints soft before will print soft after — the Book Studio editor shows the real printed resolution on every placed image, and the free 300 DPI checker gives you the same verdict without an account.
Frequently asked questions
What is the 2 MB limit for?
A+ Content images are rejected above it. That is the cap this tool defaults to, and it is a hard gate rather than a guideline — a module image at 2.4 MB does not get a warning, it gets a refusal. Interior and cover files have their own, much larger limits, which is why the size target is a choice rather than a fixed number.
Are my images uploaded?
No. Every file is decoded, re-encoded and packed into the zip on your own device — there is no server in the loop and no account to make. The one way anything leaves is the Book Studio button, and only if you press it.
Why does it stop at ten files?
Because the work happens in your browser, and ten full-size photographs is about what a tab holds comfortably without swapping. It is not a paywall — there is nothing to meter here. Drop the next ten when the first batch finishes.
How small will it go?
As small as it can without visible damage, and then it stops and tells you. There is a quality floor: rather than grinding down to something unprintable that technically met your cap, it reports the best size it actually reached and says so. When that happens the honest fix is fewer pixels, not more compression.
Which format should I pick?
Keep the format you have unless you have a reason. JPEG is smallest for photographs and is what A+ Content wants; PNG is lossless and right for flat art, logos and anything with text or transparency; WebP is smaller again but Amazon's print pipeline does not take it, so use it for the web rather than for a book.
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