Sizes & threads
Pipe & thread sizing
Nominal pipe sizes, NPT, compression, slip joint and hose thread.
Pipe & thread sizing
Pipe is called out by its nominal size, not the number on your tape measure — a 1/2 inch pipe measures larger than that on the outside. When in doubt, bring the old piece in and we'll size it at the counter.
| Nominal size | Typical use | Good to know |
|---|---|---|
| 1/2" | Branch supply to sinks, toilets and hose bibs | The most common repair size in a house |
| 3/4" | Main supply runs, water heaters, irrigation mains | Also the standard garden hose thread |
| 1-1/4" | Bathroom sink drain and P-traps | Slip joints, not glued |
| 1-1/2" | Kitchen sink drains, tub drains, disposals | Step up from bath sink — don't mix them |
| 2" | Shower drains and branch waste lines | Schedule 40 DWV fittings |
| 3" / 4" | Toilet waste and main building drain | Leave main line work to a licensed plumber |
Know your threads
NPT (tapered pipe thread)
Metal and PVC threaded fittings. Seal with thread tape or pipe dope — the taper does the sealing.
Compression
Angle stops and supply tubes. Nut plus ferrule; no tape on the ferrule threads.
Slip joint
P-traps and tailpieces. A nylon washer seals it — hand-tight plus a nudge.
Garden hose thread (GHT)
3/4" straight thread on hose bibs, splitters and washer hoses. Uses a rubber washer.
Flare
Gas and some ice-maker lines. Metal-to-metal seal — never tape a flare face.
We cut and thread pipe, and we sell fittings one at a time — no ten-pack when you need one elbow.