Shopify bundles: 2048 combinations. A bundle that creates a native Shopify bundle product must stay under 2048 variant combinations. This is checked immediately, as you're typing, not only when you save. If you exceed it while still creating the bundle, you'll see: "2048 max combinations for Shopify bundle. You have {count}. Reduce product variants or select Physical bundle type." Once the bundle is saved and you're editing it, the message drops the Physical-type suggestion, because the bundle's type can no longer be changed at that point: "2048 max combinations for Shopify bundle. You have {count}. Reduce product variants."

Physical bundles: 250 price combinations. A Physical bundle holds at most 250 distinct price combinations. This counts distinct price outcomes, not raw variant permutations — variants that share the same price and compare-at price are deduplicated first. Exceeding it blocks save: "250 max price combinations for this bundle type. You have {count}. Reduce product variants."

Widget-only bundles have no such limit.

When the server fails to generate combinations for a Shopify bundle, you'll see: "Failed to generate combinations. Please check your settings and try again. Try reducing the number of products or product variants. Note: the 'Uncombined quantity' and 'Optional products' settings significantly increase the number of possible combinations." That note names the two settings responsible for the fastest growth in combination count.

The combination count is the cartesian product of every group's selectable variants. On top of that:

For the Physical bundle's 250-price check specifically, variants that share the same price/compare-at price pair are deduplicated before counting, so 250 measures distinct price outcomes rather than every possible variant permutation.

If you hit either cap: the fastest fixes are reducing the number of selectable product variants, and checking whether Uncombined quantity or Optional products are turned on where they don't need to be. On a bundle you're still creating (not yet saved), switching to Physical bundle type is also an option if the Shopify 2048 cap is the problem — that option disappears once the bundle has been saved once.

Add new product variants to product bundle automatically (Advanced tab → Advanced settings card) appears on a Widget-only bundle built from Separate products, Product groups, Volume discount or Buy-X-Get-Y, where the source is specific products (not Collections or All store). With this on, the bundle automatically picks up any new variant you later create on those products — provided the product was originally added to the bundle with all of its variants selected. The new variant then appears in that row's selector without you needing to re-save the bundle.

Pre-select the first available product variant in the widget (Advanced tab → Advanced settings card) appears on Separate products, Product groups, Volume discount and Buy-X-Get-Y bundles. With this on, every row opens with a variant already chosen — following the same resolution order as Default variant: your pinned default first, then a variant no other row has already taken, then the first available one, then simply the first. Turning it on means several copies of the same product open on different variants by default, which is what makes the "different size on each copy" recipe work smoothly. With it off, every selector starts empty, except for a product with exactly one variant.

Product variant selection: Select variant for each item / Select once for the entire bundle (Advanced tab → Advanced settings card) appears only on a Volume discount bundle. "Select variant for each item" gives the shopper one variant selector per unit in the tier — a numbered list of selectors (#1, #2, #3) as long as the tier's quantity. "Select once for the entire bundle" gives a single selector that applies to the whole quantity.

This setting is the Volume-discount structure's counterpart to Uncombined quantity — they're different settings on different structures, doing the equivalent job for their own structure.

Product variant selection: current page product / first in list (Advanced tab → Advanced settings card) appears only on a Product groups bundle. It decides which product each slot shows before the shopper touches it. With "current page," the order is: the product of the page the shopper is currently on (if it's in the group and available), then the first available product no other group has already taken, then any available product, then the first one you listed. With the List template specifically, the current page's product wins even if it's out of stock.

Variant display (Widget customization → General settings) is a shop-wide setting, not a per-bundle one. "All variants in one selector" gives each row a single dropdown listing full variant titles. "Swatches / separate selectors" gives each row one control per product option (for example, a swatch strip for color and a separate selector for size). Neither option changes how many rows the widget shows — it only changes how each row's variant picker is drawn.