Standard Book Printing Sizes at KDP, IngramSpark, and Lulu

A platform-by-platform breakdown of standard book printing sizes — which trim sizes each service supports, where they overlap, and which to choose for your distribution goals.

Not every print-on-demand platform supports the same trim sizes. KDP, IngramSpark, and Lulu each operate with different press equipment and different distribution partnerships, and their supported size catalogs reflect those operational realities. Choosing a trim size that only one platform supports can lock you into that platform or force you to reformat your interior for every new outlet you add.

This guide maps the size catalogs of all three platforms side by side, identifies where they agree, and gives you a framework for choosing a size when your distribution strategy spans multiple services.

Why Printing Sizes Differ by Platform

Print-on-demand presses are not universal. Each platform operates a network of fulfillment partners — print facilities that physically produce the books when an order comes in. The presses at those facilities have physical constraints on what sizes they can cut, bind, and fulfill economically.

KDP fulfills most orders through its own Amazon print facilities. Their catalog prioritizes sizes that sell in volume on Amazon — which skews toward standard trade paperback and mass-market-adjacent sizes.

IngramSpark operates through Ingram's global network of Lightning Source print facilities, which were established to serve the traditional publishing industry. Their catalog is broader because they historically served publishers who needed a wide range of formats.

Lulu operates its own print network and also licenses production to third-party facilities. Their catalog includes some hobbyist-oriented sizes that neither KDP nor IngramSpark support, particularly in the square and photo-book categories.

For most authors, the practical consequence is straightforward: if you want to publish on all three platforms without reformatting, you need to pick a size that all three support. There are several safe options.

KDP Standard Printing Sizes

KDP supports the following paperback trim sizes as of mid-2026:

Paperback (black and white interior):

5 × 8 inches
5.06 × 7.81 inches (mass market)
5.25 × 8 inches
5.5 × 8.5 inches
6 × 9 inches
6.14 × 9.21 inches
7 × 10 inches
7.44 × 9.69 inches
8 × 10 inches
8.5 × 8.5 inches
8.5 × 11 inches

Paperback (premium color interior):

6 × 9 inches
7 × 10 inches
8.5 × 11 inches
8 × 10 inches

Hardcover (KDP case laminate):

5.5 × 8.5 inches
6 × 9 inches
7 × 10 inches
8.25 × 11 inches

KDP's hardcover catalog is notably smaller than its paperback catalog. Several sizes available as paperbacks — including 5 × 8 and 8.5 × 8.5 — are not available as KDP hardcovers.

KDP does not support a standard jacketed hardcover. Their hardcover product is case laminate only (no dust jacket).

IngramSpark Standard Printing Sizes

IngramSpark supports a significantly larger catalog. Key sizes include everything KDP supports plus several additional options:

Standard trade sizes (shared with KDP):

5 × 8 inches
5.5 × 8.5 inches
6 × 9 inches
7 × 10 inches
8.5 × 11 inches

Additional IngramSpark paperback sizes:

4.37 × 7 inches (rack/airport paperback)
4.72 × 7.48 inches
5.06 × 7.81 inches
5.25 × 8 inches
5.83 × 8.27 inches (A5 metric)
6.14 × 9.21 inches
6.69 × 9.61 inches
7 × 7 inches (square)
7.44 × 9.69 inches
8 × 8 inches (square)
8 × 10 inches
8.25 × 6 inches (landscape)
8.5 × 8.5 inches

IngramSpark hardcover (cloth and jacketed options available):

5 × 8 inches
5.5 × 8.5 inches
6 × 9 inches
7 × 10 inches
8.5 × 11 inches

IngramSpark hardcovers include both case laminate (equivalent to KDP's offering) and jacketed hardcover options at the standard trade sizes. This distinction matters for authors targeting bookstores, which typically expect jacketed hardcovers for front-list titles.

Lulu Standard Printing Sizes

Lulu's catalog overlaps significantly with the standard trade sizes but includes several hobby-oriented and photo-book formats not found at KDP or IngramSpark.

Pocket book: 4.25 × 6.875 inches Digest: 5.5 × 8.5 inches US Trade: 6 × 9 inches Comic book: 6.625 × 10.25 inches US Letter: 8.5 × 11 inches A4: 8.27 × 11.69 inches Square (small): 7 × 7 inches Square (large): 8.5 × 8.5 inches Landscape: 9 × 7 inches

Lulu's hardcover catalog matches their paperback sizes at most dimensions. They support jacketed hardcovers at their US Trade (6×9) and Digest (5.5×8.5) sizes.

Lulu does not support some of the specialty sizes IngramSpark offers, and they do not support the mass-market 5.06 × 7.81 format.

The Overlap: Safest Sizes for Multi-Platform Publishing

If you want your interior PDF to work across KDP, IngramSpark, and Lulu without reformatting, these are the sizes all three platforms support:

5.5 × 8.5 inches — Trade paperback, widely used for nonfiction and commercial fiction
6 × 9 inches — The most common trade paperback size in the US market
7 × 10 inches — Textbooks, workbooks, large-format nonfiction
8.5 × 11 inches — Workbooks, technical manuals, activity books

For the majority of authors — novelists, memoirists, nonfiction writers — 6 × 9 inches is the safe default. It is universally supported, the de facto standard for trade paperbacks, and requires no compromise on distribution.

For shorter books or more intimate reading experiences (literary fiction, poetry, personal essays), 5.5 × 8.5 inches is also universally supported and produces a slightly smaller, lighter book that feels closer to a mass-market paperback.

Sizes Unique to IngramSpark

IngramSpark supports several sizes that neither KDP nor Lulu offer:

4.37 × 7 inches — Traditional rack paperback (the size you see in airport bookstores). Useful for genre fiction authors aiming at a specific market feel, but this size is not available on Amazon through KDP.
5.83 × 8.27 inches — A5 metric, standard in European publishing. Useful if you are targeting UK and EU bookstore distribution through Ingram's wholesale network.
6.69 × 9.61 inches — A larger format used by some academic and professional publishers.
Jacketed hardcover — IngramSpark is the only POD platform that offers true jacketed hardcovers at standard trade sizes, which is essential for authors pursuing traditional bookstore stocking.

These IngramSpark-exclusive options are worth considering if your distribution strategy prioritizes wholesale bookstore placement over Amazon sales volume.

Sizes Unique to KDP

KDP's 5.25 × 8 inches paperback size is not universally available on IngramSpark and Lulu. This size is a minor variant on the 5.5 × 8.5 and is not commonly used.

KDP's 6.14 × 9.21 inches and 7.44 × 9.69 inches sizes are available at IngramSpark but not Lulu. These are slight variants on the 6×9 and 7×10 standards, historically used by certain publishers to give books a slightly unusual feel. There is rarely a practical reason to choose these sizes over the standard equivalents.

The notable KDP hardcover restriction is that they offer no dust-jacket option — only case laminate. If your book concept requires a jacketed hardcover, you will need IngramSpark.

How to Choose When Distributing on Multiple Platforms

Start with your primary sales channel and work outward.

If Amazon is your primary channel and you plan to also distribute through IngramSpark for bookstores, choose 6×9 or 5.5×8.5. Both are supported by both platforms, and you can use a single interior PDF with separate cover files sized for each platform's bleed requirements.

If bookstore placement is a priority and you want a jacketed hardcover, publish the hardcover through IngramSpark only. You can still publish a paperback edition through KDP separately. Many hybrid-publishing authors use this split: KDP for the Amazon paperback, IngramSpark for the hardcover and wholesale distribution.

If you are using Lulu for its direct-sales storefront or international fulfillment options, design to the overlap sizes (6×9, 5.5×8.5, 7×10) and your file will work across all three platforms.

The key practical consideration is that cover files are platform-specific even when interior files are not. Each platform calculates spine width differently based on their paper stock and binding method. You will need to regenerate the cover template for each platform even if the interior PDF is identical.

See ingramspark for indie authors for more detail on IngramSpark's distribution network and wholesale setup.

Custom Sizes

Each platform has a different relationship with custom trim sizes.

KDP does not support custom sizes. You must choose from their published catalog. If you want a size not on their list, KDP is not the right platform for that product.

IngramSpark supports custom sizes with some constraints. Custom sizes must fall within their minimum (4 × 6 inches) and maximum (8.5 × 11 inches for paperback) dimensions, and the size must be achievable on their press equipment. Custom size books are marked as such in Ingram's catalog, and some wholesale buyers filter them out. Custom sizes also cannot be ordered in bulk at the standard wholesale discount without prior arrangement.

Lulu also accepts certain custom dimensions within their platform constraints. Custom-size books created on Lulu are typically best suited for direct sales through Lulu's storefront, as they may not distribute efficiently through third-party retail channels.

The practical advice is to avoid custom sizes unless you have a compelling design reason. Custom sizes reduce your distribution flexibility, increase the chance of retailer non-stocking, and create reformatting work if you ever want to move to a different platform. The standard trade sizes exist because the publishing supply chain was built around them.

Paper Types and Size Availability

Not all sizes are available on all paper types. This affects color books most significantly.

At KDP, premium color paper (glossy and matte) is only available for a subset of their size catalog. If you need a color interior — for a cookbook, children's book, or illustrated guide — your size options narrow to 6×9, 7×10, 8×10, and 8.5×11.

At IngramSpark, color printing is available on a broader set of sizes, but pricing increases significantly for color at non-standard sizes. Standard black and white interiors are available at nearly all supported sizes.

Cream paper, which most fiction authors prefer for its warmer tone and reduced eye strain, is available at all standard sizes on both KDP and IngramSpark.

If your book requires color interiors, verify size-paper compatibility before finalizing your trim choice. A color-interior cookbook planned for 7×7 inches may not be producible on KDP at all, forcing you to IngramSpark or a size change.

See book trim sizes guide for detailed guidance on selecting trim sizes by genre and reader expectations.

Master Comparison: All Major Sizes Across Platforms

Trim Size	KDP Paperback	IngramSpark Paperback	Lulu Paperback	Notes
4.25 × 6.875 in	No	No	Yes	Lulu pocket only
4.37 × 7 in	No	Yes	No	IS rack paperback
5 × 8 in	Yes	Yes	No	Common for short fiction
5.5 × 8.5 in	Yes	Yes	Yes	Safe universal choice
5.83 × 8.27 in	No	Yes	No	A5 metric, EU market
6 × 9 in	Yes	Yes	Yes	Most common US trade size
6.14 × 9.21 in	Yes	Yes	No	Minor 6×9 variant
6.625 × 10.25 in	No	No	Yes	Lulu comic book format
7 × 7 in	No	Yes	Yes	Square format
7 × 10 in	Yes	Yes	Yes	Large-format nonfiction
7.44 × 9.69 in	Yes	Yes	No	Minor 7×10 variant
8 × 8 in	No	Yes	No	Square, IS only
8 × 10 in	Yes	Yes	No	Workbooks, large nonfiction
8.25 × 6 in	No	Yes	No	Landscape, IS only
8.5 × 8.5 in	Yes	Yes	Yes	Large square
8.5 × 11 in	Yes	Yes	Yes	Letter size, workbooks
8.27 × 11.69 in	No	No	Yes	A4, Lulu only

Frequently Asked Questions

Which size should a first-time author use? 6 × 9 inches is the safest default. It works on all three platforms, is the most familiar format for US trade paperback readers, and produces page counts and printing costs that work economically for most book lengths. If your book is on the shorter side (under 50,000 words), consider 5.5 × 8.5 to avoid a book that looks thin on the shelf.

Can I publish the same book at different sizes on different platforms? Technically yes, but it creates confusion. Retailers and readers who encounter two different versions may leave reviews on the wrong edition or make purchase decisions based on inconsistent descriptions. If you use different platforms, use the same trim size everywhere.

Does KDP allow me to change trim size after publishing? You can update your interior file on KDP after publishing, including changing the trim size. However, changing the trim size requires you to also update your cover file. If your book already has reviews and sales history under an existing ASIN, changing the format creates some customer confusion. It is better to get the size right before publishing.

Is IngramSpark's jacketed hardcover worth the extra cost for a self-published author? It depends on your goals. If you are pursuing bookstore placement or library sales, a jacketed hardcover is the expected format and worth the investment. If your primary channel is Amazon, the KDP case laminate hardcover is cheaper to produce and functionally equivalent for most buyers.

What is the largest size I can print on KDP? KDP's maximum paperback size is 8.5 × 11 inches. For hardcovers, the maximum is 8.25 × 11 inches.

LiberScript supports all major trim sizes across KDP, IngramSpark, and Lulu — format your interior once and export correctly sized PDFs for each platform. Get started with a Day pass to format your manuscript today.