WooCommerce Advanced Product Quantity Nulled extension makes it easy to set minimum and maximum product and cart quantities. Set fixed quantities for individual products, or display interval-based quantities in a dropdown. Configure quantity limitations by user role, and customize the error messages that display if a customer tries to purchase too much.
Enable decimal quantities for specific products to allow customers to purchase in fractions. You can add a minimum, maximum and steps for fractional quantities.
Demo : https://woocommerce.com/products/advanced-product-quantity/