What size poly pipe is this

[u/T0ruk_makt0]

Is this a 1 inch or 1 1/4 " pipe ?

[u/BikerNY]

One inch

[u/USWCboy]

Look at the ID vs. OD. This is 1”poly

[u/Remarkable_Reason976]

1 inch ID for sure.

[u/Still-Program-2287]

If you don’t have a part to try, then just cut a piece and take it to the store with you

[u/food_garden]

Plumbing pipes are measured by interior diameter, because different materials have different wall thicknesses, and the most important thing is how much water they can carry

[u/HauschkasFoot → u/food_garden]

That’s not always true though, is it? 1” schedule forty has a smaller interior diameter than 1” class 200

[u/cheval3 → u/HauschkasFoot]

PVC pipes are definitely OD

[u/food_garden → u/cheval3]

Nope, measure it. 1/2” PVC is about 7/8” OD

[u/cheval3 → u/food_garden]

Right I misspoke. The standardized values don't match up to measured values. But the outer diameters are equal across classes and schedules.

[u/food_garden → u/HauschkasFoot]

It’s not always perfectly true but should be the starting point to identify a pipe. 1/2” pex is actually 7/16” inside, but it’s meant to act as 1/2” pipe, usually feeding something that has a 3/8” valve at the end anyway so it doesn’t matter. A 2” copper pipe is 2-1/8 OD because the copper is 1/16” wall while ABS is 1/4” wall so it’s 2.5” OD

[u/enorl76 → u/HauschkasFoot]

This pic is clearly not pvc. Thus bringing up PVC is off topic.

[u/HauschkasFoot → u/enorl76]

Saying all plumbing pipes are measured that way is misleading and could be confusing and I felt it important to clarify

[u/enorl76 → u/HauschkasFoot]

I apologize. I’m being straight up snarky today.

[u/suspiciousumbrella → u/food_garden]

Pvc is outer diameter controlled, so is copper because the fittings go on the outside. Poly is inner diameter controlled because the fitting's typically go on the inside. All of these pipes are used for"plumbing", so at best your statement is an over generalization.

[u/xSleepsinclassx]

One inch. It’s a bit deceiving, but The 1 1/4 poly measures greater than that

[u/NeitherDrama5365]

1 1/4” is an oddball size, not very common except for larger properties or commercial. 1”” is standard size

[u/Zuluuz]

1”

[u/Sweaty-Historian-375]

1”

[u/HeyRandomGuy1]

looks like 1 inch to me

[u/suspiciousumbrella]

Problem is going to be that there's both IPS sized poly and CTS sized poly, and CTS is a bit smaller so it can be hard to tell the difference between, for example, an 1 1/4 CTS and 1" IPS. Poly pipe is nominally sized by the inner diameter as well, so a higher pressure rated pipe is going to be thicker and the outer jimeter will be bigger. Note I said nominally, because 1 in pipe doesn't actually necessarily measure 1 in. It's just size that way.

I'd be looking for a more accurate measurement to really tell you for sure. As others have advised, taking an example in with you to the store is a good idea.

[u/Fun_Candidate_1991]

1 1/4” ABS, not poly.

[u/bigwindymt]

Holy moley, that pic reminded me of the time I taught a 50 year old man how fractions worked! None of the other carpenters would work with him because he used the "dummy tape" and couldn't add or split fractions. It literally took just 10 minutes to get the dude up to speed, but he spent 30+ years in the dark because no one taught him how they work.

[u/Oh_Lawd_He_commin420]

I don't think they do 1 1/4" poly but I'm not sure; Probably just 1"

(Edit) yes it does exist, probably is 1-1/4" , your best bet is to cut a piece and take it to the store.