The supply line pictured above has a larger nut which is also 1/2" pipe thread, and a smaller nut which is a 3/8 Faucets connectors aren't completely standardized, but most have 1/2-inch male pipe thread connectors.

Take your new faucet with you when you buy supply lines to make sure you get the right connector size. The hoses that connect the valves to the faucet have a 1/2-inch diameter … Homewerks Worldwide 3/8-in Compression 20-in Braided Stainless Steel Faucet Supply Line Barclay 2-Pack 1/2-in Compression 24-in Brass Faucet Supply Line KOHLER 1/2-in Compression 26-in Brass Riser Supply Line

Plumbing for a faucet combines hard pipe with flexible pipe. Buy whatever the faucet requires.

If the supply lines included with your new faucet aren't long enough, buy extensions. If it doesn't fit onto the shutoff valves, make another trip to the store for a couple of couplings to bridge the size gaps. To make sure the threads on your new supply lines match those on your shutoff valves, take one of your old supply lines with you to the store Pull out your new faucet and check the supply line connector Supply lines usually won’t come with your new faucet (Photo 2). The 1/2-inch supply pipes that come to the sink each terminate with a shutoff valve, and this valve is one of the two factors that determine the connector size on the faucet hose. Low-flow aerator conserves your water supply, and the washerless cartridge reduces friction ..... : 3/8" Water supply line size: 1/2" male pipe thread 1-Year warranty Pull-Out Spout The pull-out spout on this faucet lets you thoroughly clean your dishes … The bath faucet shown has a pair of 1/2" pipe thread inlets. The shut off valve is 1/2, and my connection on the supply The flex line allows the water pipe to connect to the faucet without struggling to get everything lined up perfectly. Flex line is a braided hose that is available in numerous lengths and connections used in sinks and tubs. In terms of the DEP water supply line size table, whose key component is gallons per minute, the differences are even more dramatic. Re: faucet inlet size and supply line size Author: grrua (MI) Thanks for your responses. If you measure the outside, it will be around 3/4". I'm installing a new faucet for my kitchen sink, and the supply lines included with the faucet are not only too short, but they are the incorrect size to fit on my shut off valve. Single-handle, brass faucet has a retractable pull-out spout that feature stream and spray options. 8 Inch Long 1/2 x 3/8 Inch Faucet Supply Line Connects Kitchen Sink To Water Supply Line, Braided Faucet Connector With Brass Nut Stainless Steel, 2 Pieces (1 Pair) Most manufacturers of the faucets said they have 3/4 in inlets which was just explained above. Mueller Proline 3/8-in Compression 16-in Braided Stainless Steel Faucet Supply Line

As I said above, pipe sizes really confuse me. The inlet must match the supply pipe, and it can be a 1/2-inch female pipe thread (FPT) connector for galvanized pipes, a 1/2-inch compression or sweat connector for copper pipes or a 1/2-inch barbed connector for PEX pipes. If your new supply lines are too big for the shutoff valves, you need 3/8 female Basing calculations of an average run of pipe of 50′, an 1 1/4″ line provides 16 gallons per minute.