Measure across the threads of the male part, then count the threads in one inch. 1/2" pipe thread is 0.84" across and 3/4" is 1.05", both with 14 threads per inch.
Where are the threads?
What size is the fitting?
Look for a size printed on it. If there isn’t one, hold a coin against the pipe that screws into it.
How wide is it across the threads?
Hold a coin against the end. Garden hose thread is about as wide as 3/4" pipe thread, so if this is on a hose or an outdoor faucet, go back and pick that.
You most likely have
1/2" fitting, threads inside
Female pipe thread (FIP) that takes a 1/2" pipe thread, 0.84" across.
On the package: 1/2 in. FIP, also sold as FPT or FNPT
Available on Amazon
Connect it to
Start overYou most likely have
3/4" fitting, threads inside
Female pipe thread (FIP) that takes a 3/4" pipe thread, 1.05" across.
On the package: 3/4 in. FIP, also sold as FPT or FNPT
Available on Amazon
Connect it to
Start overYou most likely have
1/2" pipe, threads on the outside
Male pipe thread (MIP), 0.84" across.
On the package: 1/2 in. MIP, also sold as MPT or MNPT
Available on Amazon
Connect it to
Start overYou most likely have
3/4" pipe, threads on the outside
Male pipe thread (MIP), 1.05" across.
On the package: 3/4 in. MIP, also sold as MPT or MNPT
Available on Amazon
Connect it to
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The name is smaller than the measurement because pipe is sold by a nominal size.
Pipe thread sizes
| Thread | Across (OD) | Threads per inch |
|---|---|---|
| 1/4" | 0.540" | 18 |
| 3/8" | 0.675" | 18 |
| 1/2" | 0.840" | 14 |
| 3/4" | 1.050" | 14 |
| 1" | 1.315" | 11.5 |
Counting the threads
Lay a tape along the threads and count the peaks in one inch. It tells sizes apart that measure alike, and it tells pipe thread from garden hose thread: 3/4" pipe thread (1.050") and hose thread (about 1.0625") are almost the same width, but hose thread has 11.5 threads per inch.
Threads on the inside
A female fitting is hard to measure across. Look for the size printed on it, or measure the male part that screws into it.
Not a threaded part?
Identify any part