The two print-on-demand platforms an indie author is most likely to publish through are Amazon KDP and IngramSpark. They do similar work — they take a print-ready file, print and bind on demand, and ship to readers — but they are not interchangeable. The same manuscript usually needs two different exports if you publish on both, and several decisions you make on one platform behave differently on the other. This note walks the practical differences.
Reach and audience
Amazon KDP prints and sells on Amazon, in every market Amazon operates in. It does not distribute to other retailers in any meaningful way.
IngramSpark prints and sells through Ingram's distribution network, which reaches independent bookshops, Barnes & Noble, libraries, university stores, international wholesalers and the broader trade. It does also list on Amazon, but the listing is treated by the algorithm as third-party rather than first-party.
Most indie authors publish on both — Amazon for direct online sales, IngramSpark for everywhere else. A few publish only on Amazon if they don't expect bookshop demand. Very few publish only on IngramSpark.
Trim sizes
Amazon KDP supports a fixed set of trim sizes and a narrow band of custom dimensions. IngramSpark supports a wider range, including some sizes Amazon does not (notably some larger and more landscape-oriented options).
If you choose a trim that Amazon doesn't support, you cannot publish on KDP. If you choose a trim Amazon supports, IngramSpark almost certainly supports it too. The safest path for both platforms: use a trim from Amazon KDP's list. See the trim size guide.
Interior file requirements
Both platforms accept a flattened PDF as the interior file. Both require fonts to be embedded. Both want 300 DPI images at printed size.
Differences:
- Colour space. KDP accepts RGB or CMYK. IngramSpark prefers CMYK for colour interiors; an RGB file is converted on their side, sometimes with shifts.
- Bleed extension. Both require 0.125 in. Practically identical.
- Page-count limits. KDP caps at roughly 828 pages absolute, lower for some trims. IngramSpark allows higher counts in some configurations, up to ~1,200 in certain trims.
- Margins. Both have similar minimums. IngramSpark recommends slightly wider inner margins (gutter) for very long books than KDP requires.
A file that meets Amazon KDP's stricter spec will usually meet IngramSpark's. The reverse isn't true.
Cover file requirements
This is where the two diverge most.
KDP's cover spec calls for a single flat PDF spread: back cover, spine, front cover, with 0.125 in of bleed on every outer edge. The spine width formula uses paper-bulk multiples that depend on paper type. The barcode safe zone is 2 × 1.2 in in the bottom-right of the back cover.
IngramSpark's cover spec is structurally similar but with its own dimensions. IngramSpark uses 0.125 in bleed too, but the spine arithmetic uses different per-page thickness numbers (close to KDP's but not identical). IngramSpark expects the cover to be downloaded from their cover template generator rather than computed by the author — the template comes pre-marked with the trim, spine, fold lines and barcode zone for the specific book.
You cannot upload the same cover PDF to both platforms. The dimensions will be slightly off. Build two covers from the same source artwork.
ISBN handling
KDP issues a free ISBN automatically if you don't supply one. That ISBN is registered to "Independently published" and is restricted to Amazon — you cannot use it elsewhere.
IngramSpark requires you to supply your own ISBN. You can buy one from your country's ISBN agency (Nielsen in the UK, Bowker in the US) and use it across both platforms — which is the right move if you want a single ISBN that follows the book to all retailers.
If you only publish on Amazon, the free KDP ISBN is fine. If you publish on both, buy your own and register it on both.
Royalties and pricing
KDP pays 60% of list price minus print cost for paperbacks and hardbacks. IngramSpark pays 45% of list price minus print cost when sold through their wholesale channel, which is closer to traditional publishing economics — the lower percentage is because Ingram is also paying the bookshop or retailer that ordered the book.
Net royalty per copy is usually higher on Amazon for direct online sales, and higher on IngramSpark for any sale that goes through a bookshop or library. The practical move is to set list prices that work in both channels and let each platform handle its own market.
Returns
KDP paperbacks are non-returnable from Amazon's side, which means bookshops won't stock them. IngramSpark titles can be set to "returnable" — the bookshop can return unsold copies to Ingram for a refund — and bookshops generally won't order books that aren't returnable. If you want bookshop placement, IngramSpark with returns enabled is the route.
Returns cost money. Each return is deducted from your royalties, and a high return rate can produce negative monthly statements. Most indie authors enable returns when the book has a real chance of bookshop placement, and disable them when it doesn't.
Production turnaround and proofs
KDP proof copies arrive in 5–10 business days in most markets. IngramSpark proofs are 7–14 business days and cost more per copy. Both are worth ordering — a printed proof catches things the on-screen preview misses.
When to use which
Most indie authors use both:
- Amazon KDP for direct Amazon listings and Kindle eBooks.
- IngramSpark for everything else — bookshops, libraries, international wholesalers, non-Amazon retailers, hardback editions where IngramSpark's options are wider.
The duplication is annoying but worth it. The audiences are different. The economics are different. The cover and interior files are slightly different. Plan for two exports from the start, not one.
Where Folio Format fits
Folio Format treats KDP and IngramSpark as separate export targets. The same manuscript produces a KDP-spec PDF and an IngramSpark-spec PDF from a single project, with the cover dimensions, paper-bulk maths and bleed configuration adjusted per platform. The author makes the platform choice; the studio prepares both files.