Duct Increasers | McMaster-Carr

Filter by

Duct Size

Shape

Component

Material

Fitting Connection

Quick-Disconnect Clamp

Gender

Finish

Gauge

End Construction

Duct Profile

Duct Type

Performance

Export Control Classification Number (ECCN)

REACH

RoHS

DFARS Specialty Metals

Exempt

Forward

How can we improve?

177 Products

Standard Duct and Fittings

Deliver air for a range of HVAC applications, including exhaust and dust collection. Our basic duct, the round shape creates smoother, more efficient airflow than rectangular and oval duct. The male end is slightly smaller than the female, so sections join without clamps or tools.

Straight Reducers

Transition between duct of different diameters. Reducers also join larger duct with smaller duct that connects to equipment.

Galvanized Steel—Corrosion resistant and affordable, galvanized steel is the most commonly used ductwork material.

Corrosion-Resistant 304 Stainless Steel—The most corrosion-resistant metal duct we sell. It won’t rust or degrade in systems that exhaust chemical fumes or vent heat from industrial ovens and dryers.

Lightweight Aluminum—One-third the weight of steel, aluminum ductwork is easier to handle during installation. Like galvanized steel, it resists rust in wet environments but won’t last as long.

	Duct Size		ID		OD		Galvanized Steel			Corrosion-Resistant 304 Stainless Steel			Lightweight Aluminum
	(A)	(B)	(A)	(B)	(A)	(B)	Ga.		Each	Ga.		Each	Ga.		Each
Female × Male



		4	3	4"	—	—	2 7/8"	—	———	0	26	0000000	000000	24	00000000	000000


		4	3	4"	—	—	2 15/16"	26	0000000	000000	—	———	0	—	———	0
		5	4	5"	—	—	3 7/8"	26	0000000	00000	—	———	0	—	———	0
		6	4	6"	—	—	3 7/8"	—	———	0	26	0000000	00000	26	0000000	00000
		6	4	6"	—	—	3 15/16"	26	0000000	00000	—	———	0	—	———	0
		6	5	6"	—	—	4 7/8"	26	0000000	00000	—	———	0	—	———	0
		7	4	7"	—	—	3 7/8"	—	———	0	—	———	0	24	0000000	00000
		7	6	7"	—	—	5 7/8"	26	0000000	00000	—	———	0	—	———	0
		8	4	8"	—	—	3 7/8"	—	———	0	26	0000000	00000	—	———	0
		8	6	8"	—	—	5 7/8"	—	———	0	26	0000000	00000	—	———	0
		8	6	8"	—	—	5 15/16"	26	0000000	00000	—	———	0	—	———	0


		8	7	8"	—	—	6 7/8"	26	0000000	00000	—	———	0	—	———	0
		9	8	9"	—	—	7 15/16"	26	0000000	00000	—	———	0	—	———	0
		10	6	10"	—	—	5 7/8"	26	0000000	00000	—	———	0	—	———	0
		10	7	10"	—	—	6 7/8"	26	0000000	00000	—	———	0	—	———	0
		10	8	10"	—	—	7 7/8"	26	0000000	00000	—	———	0	—	———	0
		12	6	12"	—	—	5 7/8"	26	0000000	00000	—	———	0	—	———	0
		12	7	12"	—	—	6 7/8"	26	0000000	00000	—	———	0	—	———	0
		12	8	12"	—	—	7 7/8"	26	0000000	00000	24	00000000	000000	—	———	0
		12	10	12"	—	—	9 7/8"	26	0000000	00000	—	———	0	24	00000000	00000
		14	10	14"	—	—	9 7/8"	22	00000000	00000	24	00000000	000000	—	———	0


		14	12	14"	—	—	11 7/8"	22	00000000	00000	—	———	0	—	———	0
		16	12	16"	—	—	11 7/8"	22	00000000	00000	24	00000000	000000	—	———	0
		16	14	16"	—	—	13 7/8"	22	00000000	00000	—	———	0	—	———	0
		18	14	18"	—	—	13 7/8"	22	00000000	00000	24	00000000	000000	—	———	0
		18	16	18"	—	—	15 7/8"	22	00000000	00000	—	———	0	—	———	0
		20	16	20"	—	—	15 7/8"	24	00000000	000000	24	00000000	000000	—	———	0
		22	18	22"	—	—	17 7/8"	24	00000000	000000	—	———	0	—	———	0
		24	20	24"	—	—	19 7/8"	24	00000000	000000	—	———	0	—	———	0


		Male × Female



				4	3	—	3"	3 7/8"	—	24	00000000	00000	—	———	0	—	———	0


				5	4	—	4"	4 7/8"	—	24	00000000	00000	—	———	0	—	———	0
				6	4	—	4"	5 7/8"	—	26	0000000	00000	—	———	0	—	———	0
				7	6	—	6"	6 7/8"	—	26	0000000	00000	—	———	0	—	———	0
				8	6	—	6"	7 7/8"	—	26	0000000	00000	—	———	0	—	———	0
				8	7	—	7"	7 7/8"	—	26	0000000	00000	—	———	0	—	———	0
				10	6	—	6"	9 7/8"	—	26	0000000	00000	—	———	0	—	———	0
				10	8	—	8"	9 7/8"	—	26	0000000	00000	—	———	0	—	———	0
				12	6	—	6"	11 7/8"	—	26	0000000	00000	—	———	0	—	———	0
				12	8	—	8"	11 7/8"	—	26	0000000	00000	—	———	0	—	———	0
				12	10	—	10"	11 7/8"	—	26	0000000	00000	—	———	0	—	———	0


				14	10	—	10"	13 7/8"	—	28	0000000	00000	—	———	0	—	———	0
				14	12	—	12"	13 7/8"	—	28	0000000	00000	—	———	0	—	———	0
				16	12	—	12"	15 7/8"	—	26	0000000	00000	—	———	0	—	———	0
				16	14	—	14"	15 7/8"	—	28	0000000	00000	—	———	0	—	———	0
				18	14	—	14"	17 7/8"	—	24	00000000	00000	—	———	0	—	———	0
18				16	—	16"	17 7/8"	—	26	0000000	00000	—	———	0	—	———	0
20	18			—	18"	19 15/16"	—	24	00000000	00000	—	———	0	—	———	0
22	20			—	20"	21 15/16"	—	24	00000000	00000	—	———	0	—	———	0
24	22			—	22"	23 15/16"	—	24	00000000	00000	—	———	0	—	———	0

Tee Reducers

Connect duct of different diameters to split or merge airflow.

Galvanized Steel—Corrosion resistant and affordable, galvanized steel is the most commonly used ductwork material.

	Duct Size				OD		Galvanized Steel
	(A)	(B)	(C)	ID (A)	(B)	(C)	Ga.		Each
Female × Male × Male



		4	3	4	4"	2 7/8"	3 7/8"	26	00000000	000000


		5	3	5	5"	2 7/8"	4 7/8"	26	0000000	00000
		6	3	6	6"	2 7/8"	5 7/8"	26	0000000	00000
		6	4	6	6"	3 7/8"	5 7/8"	26	0000000	00000
		8	6	6	8"	5 7/8"	5 7/8"	24	00000000	000000
		10	8	8	10"	7 7/8"	7 7/8"	24	00000000	000000
		12	8	8	12"	7 7/8"	7 7/8"	24	00000000	000000

45° Wye Reducers


Female × Male × Male	Male × Female × Female

Connect duct of different diameters to split or merge airflow more gradually than tees. With less abrupt changes in direction, wyes reduce turbulence for smoother flow.

Galvanized Steel—Corrosion resistant and affordable, galvanized steel is the most commonly used ductwork material.

	Duct Size			ID			OD			Galvanized Steel
	(A)	(B)	(C)	(A)	(B)	(C)	(A)	(B)	(C)	Ga.		Each
Female × Male × Male



		12	10	10	12"	—	—	—	9 7/8"	9 7/8"	28	00000000	0000000


		14	10	10	14"	—	—	—	9 7/8"	9 7/8"	28	00000000	000000
		16	12	12	16"	—	—	—	11 7/8"	11 7/8"	26	00000000	000000
		16	14	14	16"	—	—	—	13 7/8"	13 7/8"	26	00000000	000000


		Male × Female × Female



				4	3	3	—	3"	3"	3 7/8"	—	—	26	00000000	00000


				5	3	4	—	3"	4"	4 7/8"	—	—	26	00000000	00000
				5	3	5	—	3"	5"	4 7/8"	—	—	26	00000000	00000
				6	3	4	—	3"	4"	5 7/8"	—	—	26	00000000	00000
				6	4	4	—	4"	4"	5 7/8"	—	—	26	00000000	00000
				6	4	5	—	4"	5"	5 7/8"	—	—	26	00000000	00000
				7	5	6	—	5"	6"	6 7/8"	—	—	26	00000000	00000
				8	6	6	—	6"	6"	7 7/8"	—	—	26	00000000	00000
				10	8	8	—	8"	8"	9 7/8"	—	—	26	00000000	000000
				12	8	8	—	8"	8"	11 7/8"	—	—	26	00000000	000000

Snap-On Drop-Ceiling Diffuser Collars

Connect drop-ceiling diffusers to duct. Use the included push-in fasteners to attach collar to diffuser.

For Duct Size	OD	Gender	Material	Each
6	5 15/16"	Male	Galvanized Steel	000000
8	7 15/16"	Male	Galvanized Steel	00000
10	9 15/16"	Male	Galvanized Steel	00000
12	11 15/16"	Male	Galvanized Steel	00000

Quick-Disconnect Duct and Fittings

The fastest ductwork to disassemble for dust collection and other frequently cleaned systems. Join sections with quick-release clamps that open and close with a flip of the latch. Since you don’t need screws, welds, or tools, the installation time is half that of other duct types.

Straight Reducers

Transition between duct of different diameters. Reducers also join larger duct with smaller duct that connects to equipment.

Galvanized Steel—Corrosion resistant and affordable, galvanized steel is the most commonly used ductwork material.

Duct Size		ID			Galvanized Steel		Corrosion-Resistant 304 Stainless Steel
(A)	(B)	(A)	(B)	Ga.		Each		Each



	4	3	3 7/8"	3 1/16"	22	00000000	000000	00000000	0000000


	5	4	4 7/8"	3 7/8"	22	00000000	00000	00000000	000000
	6	4	5 7/8"	3 7/8"	22	0000000	00000	00000000	000000
	6	5	5 7/8"	4 7/8"	22	0000000	00000	00000000	000000
	8	6	7 7/8"	5 7/8"	22	00000000	00000	00000000	000000
	10	6	9 7/8"	5 7/8"	22	00000000	00000	0000000	000000
	10	8	9 7/8"	7 7/8"	22	00000000	00000	00000000	000000
	12	8	12"	7 7/8"	22	00000000	000000	00000000	000000
	12	10	12"	9 7/8"	22	00000000	000000	00000000	000000
	14	12	13 15/16"	12"	22	00000000	000000	00000000	000000
	16	14	16"	14"	20	00000000	000000	00000000	000000


	18	16	17 15/16"	16"	20	00000000	000000	00000000	000000
	20	18	19 15/16"	17 15/16"	20	00000000	000000	00000000	000000
	22	20	22"	19 15/16"	20	00000000	000000	———	0
	24	22	23 15/16"	22"	20	00000000	000000	———	0

Chemical-Resistant Duct and Fittings

Chemicals can eat away at most metal duct, but not this PVC system. It’s often used to exhaust corrosive gases, vapors, and fumes. Components press-fit together and secure with PVC pipe cement.

Straight Reducers

Transition between duct of different diameters. Reducers also join larger duct with smaller duct that connects to equipment.

Duct Size		ID			PVC
(A)	(B)	(A)	(B)	Color		Each



	6	4	6 5/8"	4 1/2"	Gray	0000000	0000000


	8	6	8 5/8"	6 5/8"	Gray	0000000	000000
	10	8	10 3/4"	8 5/8"	Gray	0000000	000000
	12	8	12 3/4"	8 5/8"	Gray	00000000	000000
	12	10	12 3/4"	10 3/4"	Gray	0000000	000000
	14	10	14"	10 3/4"	Gray	00000000	000000
	14	12	14"	12 3/4"	Gray	0000000	000000

Spiral Duct and Fittings

Reinforced with a continuous seam, this duct keeps its shape, even against suction from dust collection systems. On the inside, duct is smooth for efficient airflow. Because of its attractive look, spiral duct is often used for exposed heating and cooling systems.

Straight Reducers

Transition between duct of different diameters. Reducers also join larger duct with smaller duct that connects to equipment.

Galvanized Steel—Corrosion resistant and affordable, galvanized steel is the most commonly used ductwork material.

Chemical-Resistant PVC-Coated Steel—This duct combines the strength of steel with the chemical resistance of plastic. More economical than 304 stainless steel and stronger than PVC, it’s often used to exhaust corrosive gases, vapors, and fumes.

Duct Size		OD		Galvanized Steel			Chemical-Resistant PVC-Coated Steel			Corrosion-Resistant 304 Stainless Steel
(A)	(B)	(A)	(B)	Ga.		Each	Ga.		Each	Ga.		Each
4	3	3 7/8"	2 7/8"	24	0000000	000000	—	———	0	24	00000000	000000
5	4	4 7/8"	3 7/8"	24	0000000	00000	20	00000000	000000	24	00000000	00000
6	4	5 7/8"	3 7/8"	24	0000000	00000	20	00000000	00000	20	0000000	00000
6	5	5 7/8"	4 7/8"	24	0000000	00000	20	00000000	00000	24	00000000	00000
7	6	6 7/8"	5 7/8"	24	00000000	00000	20	00000000	00000	24	00000000	00000
8	6	7 7/8"	5 7/8"	24	0000000	00000	20	00000000	00000	20	0000000	000000
8	7	7 7/8"	6 7/8"	24	00000000	00000	20	00000000	00000	24	00000000	000000
9	8	8 7/8"	7 7/8"	24	00000000	00000	20	00000000	00000	24	00000000	000000
10	6	9 7/8"	5 7/8"	24	0000000	00000	—	———	0	20	0000000	000000
10	8	9 7/8"	7 7/8"	24	0000000	00000	20	00000000	000000	20	0000000	000000
10	9	9 7/8"	8 7/8"	24	00000000	00000	20	00000000	000000	—	———	0
12	6	11 7/8"	5 7/8"	24	0000000	00000	—	———	0	—	———	0
12	8	11 7/8"	7 7/8"	24	0000000	00000	—	———	0	—	———	0
12	10	11 7/8"	9 7/8"	24	0000000	00000	20	00000000	000000	24	00000000	000000
14	12	13 7/8"	11 7/8"	24	0000000	00000	—	———	0	24	00000000	000000
16	14	15 7/8"	13 7/8"	24	0000000	00000	—	———	0	24	00000000	000000
18	16	17 7/8"	15 7/8"	22	00000000	00000	—	———	0	24	00000000	000000
20	18	19 7/8"	17 7/8"	24	00000000	000000	—	———	0	24	00000000	000000
22	20	21 7/8"	19 7/8"	24	00000000	000000	—	———	0	—	———	0
24	22	23 7/8"	21 7/8"	24	00000000	000000	—	———	0	—	———	0

Tee Reducers

Connect duct of different diameters to split or merge airflow.

Duct Size			OD			Chemical-Resistant PVC-Coated Steel
(A)	(B)	(C)	(A)	(B)	(C)	Ga.		Each
6	4	6	5 7/8"	3 7/8"	5 7/8"	24	00000000	000000
8	6	8	7 7/8"	5 7/8"	7 7/8"	24	00000000	000000
10	8	10	9 7/8"	7 7/8"	9 7/8"	24	00000000	000000
12	8	12	11 7/8"	7 7/8"	11 7/8"	24	00000000	000000

45° Wye Reducers

Connect duct of different diameters to split or merge airflow more gradually than tees. With less abrupt changes in direction, wyes reduce turbulence for smoother flow.

Duct Size			OD			Chemical-Resistant PVC-Coated Steel
(A)	(B)	(C)	(A)	(B)	(C)	Ga.		Each
6	4	6	5 7/8"	3 7/8"	5 7/8"	24	00000000	000000
8	6	8	7 7/8"	5 7/8"	7 7/8"	24	00000000	000000
10	8	10	9 7/8"	7 7/8"	9 7/8"	24	00000000	000000
12	10	12	11 7/8"	9 7/8"	11 7/8"	24	00000000	000000

Tight-Seal Spiral Duct and Fittings

Gasketed fittings prevent leaks between connections without the need for tape or other sealants. Duct has a continuous seam that reinforces it for strength and long life. The rigid construction keeps its shape, even against suction from dust collectors. Duct is smooth on the inside for efficient airflow. Because of its attractive look, spiral duct is often used for exposed heating and cooling systems.

Straight Reducers

Transition between duct of different diameters. Reducers also join larger duct with smaller duct that connects to equipment.

Galvanized Steel—Corrosion resistant and affordable, galvanized steel is the most commonly used ductwork material.

Duct Size		OD		Galvanized Steel with EPDM Gasket
(A)	(B)	(A)	(B)	Ga.		Each
6	4	5 7/8"	3 7/8"	20	0000000	000000
8	6	7 7/8"	5 7/8"	20	0000000	00000
10	6	9 7/8"	5 7/8"	20	0000000	00000
10	8	9 7/8"	7 7/8"	20	0000000	00000
12	8	11 7/8"	7 7/8"	20	0000000	00000
12	10	11 7/8"	9 7/8"	20	0000000	00000

Rectangular Duct and Fittings

Maximize the space in close quarters, such as inside walls and ceilings. As rectangular duct sizes increase, they get wider but not taller. This shape is most often used for heating and cooling inside buildings. Components connect with brackets.

Straight Reducers

Shown Installed

Image of Product. Front orientation. Duct and Fittings. Rectangular Duct and Fittings, Straight Reducers.

Transition between ducts of different sizes. These reducers decrease duct width by 2". Cut a hole in the smaller duct to fit the reducer and secure it with tapping screws.

Galvanized Steel—Corrosion resistant and affordable, galvanized steel is the most commonly used ductwork material.

			Galvanized Steel
Wd.	Ht.	Ga.		Each



	2"	8"	28	0000000	000000