Guide · Couplers, adapters and swivels
M22 14 mm vs 15 mm pressure washer fittings
M22 14 mm and 15 mm fittings share one outside thread but not the inner stem. How to tell which you have, and which makers state the size.
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Short answer
M22 14 mm and M22 15 mm fittings share the same 22 mm outside thread. They differ in the inner stem diameter, so a 14 mm stem in a 15 mm bore leaks and a 15 mm stem will not enter a 14 mm bore. Measure the male end's bore or read the maker's document for each part before you buy.
What "M22" means
In the name M22, the M means a metric thread and 22 is the outside thread diameter in millimeters.[1] The full designation is M22 x 1.5: a 22 mm nominal size with a 1.5 mm pitch.[2] Westinghouse labels the inlet of its PWEXT extension wand "M22x1.5 - 14mm".[3]
So "M22" alone describes only the thread. It says nothing about the stem inside it, and that is where the seal is made.
14 mm and 15 mm: same thread, different stem
The 14 mm and 15 mm versions have identical outside threads and differ only in the inner stem diameter, so they can screw together and still not seal.[1] AR Blue Clean says a 14 mm stem in a 15 mm bore will leak, and a 15 mm stem will not fit into a 14 mm bore.[1]
The 14 or 15 mm figure is the stem, not the hose's inside diameter. A 1/4 in hose and a 3/8 in hose can both carry a 14 mm M22 end.
How to tell which one you have
AR Blue Clean recommends two ways: measure the inner bore of the male M22 connection, or check the product documentation for the internal diameter.[1] AR calls measuring the male bore the most accurate method. It gives no tolerance figure, and neither do we.
Measure on a part that is disconnected from the machine. Read the document for the exact model, not the brand: makers change parts between models and generations.
What AR Blue Clean says in general
AR Blue Clean says 14 mm M22 fittings are common on aftermarket hoses and gas pressure washers, while many electric pressure washers and their accessories use 15 mm.[1] That is one maker's general observation, with no model list. It is a reason to check, never a way to assign a size to your machine.
Where makers state the bore
These are the parts and machines whose maker names the stem size in a document we read:
- Active 2.0: Active Products says the hose and gun connections are M22-14 mm, and the lance has a 1/4 in quick-connect outlet.[4] See the Active 2.0 page.
- Flexzilla pressure washer hoses: Flexzilla's table lists all eight SKUs with M22 fittings on a 14 mm stem.[5]
- Westinghouse PWEXT wand: the manual lists a male M22-14 inlet.[3]
- DEWALT DXPA25PH hose: DEWALT says it uses M22 connections and includes a 14/15 mm M22 connector.[6]
| Label | Outside thread | Inner stem | Maker-stated examples |
|---|---|---|---|
| M22 x 1.5, 14 mm | 22 mm, 1.5 mm pitch | 14 mm | Active 2.0 hose and gun; Flexzilla HFZPW hoses; Westinghouse PWEXT inlet |
| M22 x 1.5, 15 mm | 22 mm, 1.5 mm pitch | 15 mm | Inlet of AR Blue Clean's PW554-B adapter |
| M22, size not stated | 22 mm | Check the part | Many listings; DEWALT DXPA25PH ships a 14/15 mm connector |
O-rings are part-specific
The O-ring sits on the stem, so its size follows the part. ProPulse lists its consumer UberFlex hose O-rings as 14 mm OD x 10 mm ID x 2 mm and says it does not sell replacements.[7] Champion's 100384 parts list shows a 14 x 9 x 2.5 mm O-ring at the hose and wand connections.[8] Those are two different sizes for two different parts. Order the O-ring the maker lists for your part.
Adapters named by inner size
When the two ends differ, an adapter bridges them only if its maker names both:
- AR Blue Clean's PW554-B has a 15 mm M22 swivel inlet and a male M22 x 14 mm outlet.[9] AR lists no pressure rating for it.[9]
- MTM Hydro sells separate M22 adaptor kits for 14 mm and 15 mm connections, in stainless steel or brass.[10] It names its M22 adapters by inner size, such as an M22 plug (14 mm) by 3/8 in stainless QC coupler.[10]
More on reading both ends is in the adapter guide.
Parts that state the size
Picks that fit2 products
Choose the Flexzilla HFZPW3425M (1/4 in x 25 ft) only if both your pump outlet and gun take a 14 mm M22 end; Flexzilla states the 14 mm stem and 3,100 PSI at 70°F, so your machine's maximum must be at or below that.
More on choosing
The Sun Joe adapter is sold for Sun Joe's SPX series: read both ends on Sun Joe's listing and confirm Sun Joe recommends it for your model. On Amazon, check that 'Ships from / Sold by' shows Amazon.com or the brand.
M22 hose with a stated 14 mm stem
Flexzilla HFZPW3425M pressure washer hose, 1/4 in x 25 ft, M22 (14 mm stem)
Sun Joe's own M22 adapter for its SPX series
Sun Joe SPX‑M22M2F 14 mm M22 male to 15 mm M22 female high-pressure hose adapter, brass
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Questions
What is the difference between M22 14 mm and 15 mm?
Both have the same 22 mm outside thread. They differ in the inner stem diameter, 14 mm or 15 mm, which is where the O-ring seals.[1]
Why does my M22 fitting screw on but leak?
The thread can match while the stem does not. AR Blue Clean says a 14 mm stem in a 15 mm bore will leak, and a 15 mm stem will not go into a 14 mm bore. Do not force or over-tighten it; find the right part.[1]
How do I know if my pressure washer is 14 mm or 15 mm?
Measure the inner bore of the male M22 end, or read the maker's documentation for that model. We do not name a size for a whole brand, because no maker document we read does.[1]
Can I use a 14 mm hose on a 15 mm machine?
Only through an adapter whose maker states both ends, such as AR Blue Clean's PW554-B (15 mm swivel inlet, 14 mm male outlet). Check that the adapter's rating covers your machine; AR states none for the PW554-B.[9]