Selling product per set amount (selling per tray/box)

Technical Q&A

Topic summary

Goal: Sell items only in fixed pack sizes (e.g., trays of 6), while displaying the price per single unit. Cart quantities must increment by the pack size.

Current setup: A workaround uses the Shopify “vendor” field to store the pack size (e.g., 6). The quantity stepper on the product page jumps 6→12→18, and the total price multiplies accordingly. Screenshots show this behavior and a checkout error.

Issue: At checkout, quantity validation sometimes fails with a browser message (“Please enter a valid value. The two closest valid values are 12 and 24.”). Removing and re-adding items can temporarily fix it, but the error may recur on other products, creating friction.

Constraints: Creating variants for many quantity options is impractical due to large order ranges (6 to 6000). The requester has a metafields app and seeks guidance/apps to enforce pack multiples while showing per-unit price.

Suggestions so far: Price the product per pack (set-of-6) in Shopify and show the per-bottle price in the description, since single units aren’t sold. Metafields were mentioned but need clearer guidance.

Status: Unresolved; looking for a robust, app- or metafields-based solution to enforce pack multiples and display per-unit pricing without checkout errors.

Summarized with AI on January 29. AI used: gpt-5.
1

I only want to sell products per tray/box.

Let’s say there are 6 bottles in a tray, then I only want to sell these bottles per 6 pieces. However, the price of the product must be shown for 1 bottle. If the customer puts the bottles in his/her shopping cart, this should only be possible in increments of 6.

I have made some kind of workaround that when I enter a number in the ‘vendor’ field of a product, it only adds this product to the shopping cart per that amount. So with the example of the bottles, I entered a 6 in the vendor field.

On the front end it looks like this:

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When a customer presses the ‘+’, it flicks to 12, then 18, 24 and so on. The price of the product will be multiplied by the amount added to the cart.

The problem is that this sometimes gives errors when customers try to check out. It refuses to accept the amount and keep saying that the customer should change it.

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Translation: ‘Please enter a valid value. The two closest valid values are 12 and 24.’
Deleting the product from the shopping cart and re-adding it helps, but it then sometimes shows this error immediately for another product in the cart. Which makes it very frustrating for customers to finish their order.

TLDR: I’m not very good with custom code so I am looking for an app that lets me sells products only per set amount, but shows the price in the store of just 1 piece.
Let me know if you need more info in order to help.

2

Thank you for your reply!

Variants are not really an option since there are customers that order 6 pieces, but also customers that order 6000 pieces. That would mean I would have to add a loooot of variants to each product.

Could you maybe tell a bit more about the metafields option?
I do have the ‘Metafields Custom Field Manager’ app.

3

I think you should set the unit price per set-o- 6 and then show the price per bottle in the product description for information purposes. Since you don’t sell per bottle, it’s not of any use to set the price on Shopify per bottle.