Not always—they’re related, but not necessarily identical in size or function. Faucet coupling nuts are typically used to connect the faucet to the water supply lines. The most common sizes are: - 1/2 inch (standard for many bathroom and kitchen faucets) - 3/8 inch (often used for flexible supply lines) - 3/4 inch (common for outdoor or utility faucets) Faucet mounting nuts (often just called “faucet nuts”) are used to secure the faucet body to the sink or countertop. These are usually: - 7/8 inch hex nuts or larger - Threaded differently than coupling nuts - Often made of plastic or metal, depending on the faucet type So while both are “nuts” used in faucet installations, they serve different purposes and may not be interchangeable. If you’re replacing a part, it’s best to check the thread size and application—especially since coupling nuts are usually female-threaded to fit onto male-threaded faucet inlets or supply lines.