WooCommerce has no built-in minimum order setting. Here are the two ways to add one, a plugin or a code snippet, plus a step-by-step setup that blocks checkout below your threshold.
The short answer: WooCommerce has no built-in setting for a minimum order amount, so you add it with a small plugin or a code snippet. A plugin is the safer choice for most stores because it shows a clear message at the cart and blocks checkout until the customer reaches the minimum, without you touching theme files.
A minimum order protects your margins. If your packaging, payment fees and courier cost about the same whether an order is 5 euros or 50, then very small orders can lose you money. A sensible minimum, by value or by quantity, nudges customers to add one more item and keeps every order worth fulfilling.
Common reasons stores set one:
A plugin such as ShopBoost lets you set a minimum order total or a minimum quantity, write the message customers see, and decide whether the rule applies to everyone or only certain roles. Checkout stays blocked until the cart meets the rule, and the message updates live as the customer adds items. Nothing in your theme changes, so an update or a theme switch will not break it.
If you prefer code, you can hook into woocommerce_check_cart_items, then add a notice and an error when the cart total is below your threshold. It works, but you own it forever: you maintain it, you translate the message yourself, and a mistake shows errors to real customers. For a single fixed rule it is fine. For anything flexible, a plugin pays for itself quickly.
WooCommerce will not stop tiny orders on its own, so set a minimum that matches your real costs. A plugin like ShopBoost gives you a flexible rule, a clear message and a blocked checkout in a couple of minutes, with nothing to maintain in your theme.