Min Max Quantity and Step Control for WooCommerce

Set a minimum quantity, a maximum quantity, a step and a starting quantity on each product. A figure on the product wins. A blank box uses the shop default. A minimum of zero on a product means that product has no minimum, and it wins over the shop default.

The series starts at the minimum when there is one, and at 1 when there is not. A minimum of 4 and a step of 2 allows 4, 6 and 8. A minimum of 3 and a step of 2 allows 3, 5 and 7. A step of 2 with no minimum allows 1, 3 and 5, which is what the quantity box itself will accept. A starting quantity is shown when it lands on that series. One that falls between two steps, or below the minimum, is replaced by the first number the box will accept.

A variation uses its own figures where it has them, then its parent's, then the shop defaults. Variations that leave the boxes blank and share the parent's minimum, maximum or step are counted together, so two variations of one product add up to the parent's limit. A variation with its own figures is judged on its own.

The quantity box on the product page, in the shop loop and in the cart follows those figures. Adding to the cart, and changing a quantity already there, is refused when the total falls outside the rule. Classic checkout cannot place the order while a quantity is outside the rule. The Cart and Checkout blocks use the same minimum, maximum and step through WooCommerce's Store API, and refuse the same quantities. PayPal and other express buttons stay on the cart, so the customer can read why the order is not going through, and the order itself is refused before the customer is sent out to pay. A short message appears under the quantity box when the quantity is under the minimum or over the maximum, and the three short sentences are edited under Messages, with the placeholders {min}, {max} and {step}.

When some of the product are already in the cart, the box offers the next quantity the total will allow. Three already in the cart and a series of 3, 5 and 7 cannot take another 3, because 6 is not on the series, so the box does not offer 3.

Stock still wins. A quantity above the stock on hand is refused even when the maximum is higher, and a product sold individually stays at one. If the minimum is higher than the stock, the customer is told both figures rather than asked to add more than can be bought. The message is one you write. Bold, italics and links are allowed, and the placeholders {product}, {min}, {max}, {step}, {quantity} and {stock} are filled in when it is shown. It appears on the cart, at checkout and in the mini-cart. The shortcode [mmqswc_message] prints the same sentence anywhere else, and shows nothing once the cart is fine.

A current licence adds rules on top of those figures. A role replaces the product's own figures, so wholesale and retail are not held to the same quantity. A product category, a tag or a shipping class fills only what the product left blank. A combined quantity adds the matching lines for a category, a tag, a shipping class, or the whole cart, and it applies only when the cart contains something from that group. An exempt role is not held to these limits. Stock and sold individually stay WooCommerce's either way. Each rule can carry its own message. Bulk edit and a CSV set the same limits across the catalogue, and those rules travel with an export of the settings.

If the licence lapses, nothing is deleted. The extra rules stay on the screen as words you can read but not change, and every customer is held to the product figures and the shop defaults. Renewing switches those rules back on as you left them. Nothing is written to an order, so High-Performance Order Storage is supported in the same way.