Image processing for Amazon Merch and KDP sellers
Amazon's rejection bot is unforgiving. We get the DPI, dimensions, and format exactly right — so every Merch, KDP, and FBA upload sails through on the first try.
Challenges we solve
Common problems that slow down your workflow — and how Ratio Ready handles each one.
Strict Amazon image specifications
Amazon's Merch on Demand requires exact pixel dimensions and 300 DPI for every product type. One wrong setting and your upload is rejected, sending you back to resize and re-export.
Different requirements for Merch vs KDP
A t-shirt design needs different dimensions than a KDP book cover, which is different again from a phone case or tote bag. Keeping track of specs across product lines wastes time and causes errors.
Scaling designs across multiple products
When you have a winning design, you want it on every product type. But manually creating 10+ size variants of the same design is tedious work that slows your catalog expansion.
Time-consuming manual image preparation
Between resizing, DPI conversion, format changes, and quality checks, image prep for Amazon can take longer than creating the design itself. That time adds up when you're scaling to hundreds of listings.
Meet Amazon's requirements automatically
Upload once and get files formatted exactly how Amazon expects them -- no manual resizing or DPI guessing.
- Automatic 300 DPI conversion for all outputs
- Correct pixel dimensions for every product type
- PNG output with transparency support for Merch
- High-resolution output for KDP covers and interiors
- AI upscaling when source images are too small
- Batch processing for scaling across product types
- ZIP download with organized, ready-to-upload files
- REST API for automated workflows with Make.com or n8n
- No software to install -- works in your browser
- Pay-per-image credits with no monthly commitment
Your workflow with Ratio Ready
Upload your artwork
Drag and drop your designs into Ratio Ready. We accept JPG, PNG, and WebP files up to 50MB. Images with transparent backgrounds are preserved for Merch on Demand products.
Select your output settings
Choose the print size and resolution you need. Ratio Ready shows you exactly what each image will cost to process, including whether AI upscaling is needed for undersized files.
Process to Amazon's specs
One click converts your designs to 300 DPI at the correct dimensions. Each file is validated and processed in seconds, not minutes. Batch up to 50 images at once.
Download ready-to-upload files
Get a ZIP file with all your processed images organized and named. Upload directly to Amazon Merch on Demand or KDP without any additional editing or conversion.
When you’d use this
Four common scenarios where Ratio Ready saves the most time:
- Scaling a single winning design across the Merch catalog. You have a design that's selling on a t-shirt. To put it on a hoodie, tank, mug, and tote you need different pixel dimensions for each product. Ratio Ready outputs the right size for every Merch product type from one upload — no manual re-export per product.
- Preparing a KDP book cover with exact bleed. KDP wants 300 DPI with bleed at the precise trim size. Ratio Ready's poster maker outputs to your exact dimensions and stamps 300 DPI metadata, so the file passes KDP's pre-press check on the first upload.
- Recovering from Amazon's rejection bot. Amazon flagged your file as too low-res or wrong format. Drop the source into Ratio Ready, set the target dimensions, let AI upscaling handle the resolution gap. Re-upload to Amazon and pass on the first retry.
- Building a 50-design Merch collection. Batch processing handles up to 50 designs in one ZIP. Set the target dimensions once, hit process, get back a folder of Amazon-ready PNGs in 60-90 seconds. Replaces 4+ hours of one-at-a-time Photoshop work.
Common mistakes
Mistakes I’ve seen (and made) that cost real time and refunds:
1. Designing at 72 DPI then trying to scale up at upload time
Amazon's bot reads DPI metadata, not visual quality. A 72 DPI file with plenty of pixels still gets flagged. Always design at 300 DPI from the start, or run through Ratio Ready (300 DPI stamped automatically on every output).
2. Using JPG for Merch designs that need transparent backgrounds
JPG cannot store transparency. Designs with transparent backgrounds saved as JPG fill with white — making them unusable on coloured Merch products. Always use PNG (with alpha) for any design with transparent regions.
3. Sourcing images from web downloads
Most web images are 72 DPI and undersized. Even after upscaling, they may have JPEG compression artifacts that show up at print size. Source from your own design tools or paid stock sites where dimensions are verified.
4. Forgetting that KDP and Merch have different specs
A t-shirt design at 4500×5400 won't fit a KDP book cover (which needs trim size + bleed). Mixing up product specs causes rejection cycles. Run each design through Ratio Ready with the correct target per product type.
5. Skipping AI upscaling on borderline-size source files
A 3,500-pixel design will print sharp at 12 inches but soft at 15. If your Merch product needs 4,500 pixels and your source is 3,500, run AI upscaling first. Ratio Ready detects this and offers it inline.
Frequently asked questions
Related guides
Print-Ready Files for Amazon
Amazon Merch, KDP, and FBA product image specs — cover sizes, bleed, and color modes.
How to Batch Resize Images for POD
Resize multiple designs at once for different Amazon product types.
DPI Explained for POD Sellers
What DPI means and why Amazon requires 300 DPI for all print products.
Get Amazon-ready images in seconds
50 free credits to process your first designs. No credit card required.