Round to rectangular adapter 3D models

First model: 2025-08-30

Number of 3D models generated: 878

Category: technical parts

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Photos of various 3D printed models

This template allows the generation of adapters from a circular section to a rectangular section. It can find applications in fluid transfer systems, whether involving liquids (water flow) or gases (airflow).

Beyond the parameters inherent to this type of part, additional parameters include the possibility of applying an axis offset along the Y and Z axes.

It is also possible to apply chamfers to the ends to facilitate tube insertion.

A stop at the end of the rectangular section prevents the tube from moving further.

The design has been optimized to facilitate fluid flow rather than applying a sharp transition (through a simple loft).

The vast majority of these models can be printed without support, by laying the cylindrical side on the print bed.

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Keywords: round-rectangular connector, round-rectangular transition piece, circular-rectangular adapter, round-rectangular fitting, circular tube to rectangular tube transition, round duct to rectangular duct adapter, rectangular adapter

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	name	unit	Value	Weight
#1	cylinder outer diameter 20 to 300 – up to 1 decimal place	mm
#2	cylinder inlet length 5 to 100 - integer	mm
#3	rectangle internal length 5 to 300 – up to 1 decimal place	mm
#4	rectangle internal height 5 to 300 – up to 1 decimal place	mm
#5	rectangle inlet length 5 to 100 - integer	mm
#6	offset Z 0 to 300 – up to 1 decimal place	mm
#7	offset Y 0 to 300 – up to 1 decimal place	mm
#8	total length 50 to 300 – up to 1 decimal place	mm
#9	thickness 2 to 5 - integer	mm
#10	chamfer		-	-
			Search

Additional information

See 3d modeling details

• If the chamfer option on the ends is enabled, the chamfer length is equal to half the thickness.
• The stop at the bottom of the rectangular section has a width equal to half the thickness.

Illustration of the parameters

Categories

Round to rectangular adapter
Cylinder outer diameter
20 to 100 mm

Round to rectangular adapter
Cylinder outer diameter
100 to 150 mm

Round to rectangular adapter
Cylinder outer diameter
150 to 200 mm

Round to rectangular adapter
Cylinder outer diameter
200 to 250 mm

Round to rectangular adapter
Cylinder outer diameter
250 mm and over

The latest online-generated models

Round-to-Rectangular Tube Adapter STL file ⌀100 mm to 104×27 mm, thickness 2 mm + offset (📦 #10204)

1 object(s) - format STL

Download this file in STL format of a round-to-rectangular tube adapter with an external diameter of ⌀100 mm and a rectangular section with internal dimensions 104×27 mm. The wall thickness is 2 mm and the overall length is 200 mm. The adapter has an offset of 50 mm along the Z axis.

Parameter	Value	Unit
cylinder outer diameter	100	mm
cylinder inlet length	25	mm
rectangle internal length	104	mm
rectangle internal height	27	mm
rectangle inlet length	25	mm
offset Z	50	mm
offset Y	0	mm
total length	200	mm
thickness	2	mm
chamfer	no chamfer

Round-to-Rectangular Tube Adapter STL 3D file ⌀124 mm to 224×94 mm, thickness 3 mm (📦 #10172)

1 object(s) - format STL

Download this file in STL format of a round-to-rectangular adapter with an external diameter of ⌀124 mm and a rectangular section with inner dimensions 224×94 mm. The shell thickness is 3 mm and the overall length is 130 mm.

Parameter	Value	Unit
cylinder outer diameter	124	mm
cylinder inlet length	50	mm
rectangle internal length	224	mm
rectangle internal height	94	mm
rectangle inlet length	50	mm
offset Z	0	mm
offset Y	0	mm
total length	130	mm
thickness	3	mm
chamfer	no chamfer

Round-to-Rectangular Tube Adapter STL file ⌀124 mm to 224×94 mm, thickness 3 mm (📦 #10171)

1 object(s) - format STL

3D model in STL format of a round-to-rectangular tube adapter with an outer diameter of ⌀124 mm and a rectangular section with inner dimensions 224×94 mm. The shell thickness is 3 mm and the overall length is 50 mm.

Parameter	Value	Unit
cylinder outer diameter	124	mm
cylinder inlet length	10	mm
rectangle internal length	224	mm
rectangle internal height	94	mm
rectangle inlet length	10	mm
offset Z	0	mm
offset Y	0	mm
total length	50	mm
thickness	3	mm
chamfer	no chamfer

Round-to-Rectangular Tube Adapter STL file ⌀95 mm to 110×32 mm, thickness 3 mm + offset (📦 #10141)

1 object(s) - format STL

Download this 3D model in STL format of a round-to-rectangular adapter with an external diameter of ⌀95 mm and a rectangular section with internal dimensions 110×32 mm. The wall thickness is 3 mm and the total length is 120 mm. The adapter has an offset of 20 mm along the Z axis.

Parameter	Value	Unit
cylinder outer diameter	95	mm
cylinder inlet length	50	mm
rectangle internal length	110	mm
rectangle internal height	32	mm
rectangle inlet length	30	mm
offset Z	20	mm
offset Y	0	mm
total length	120	mm
thickness	3	mm
chamfer	no chamfer

Round-to-Rectangular Tube Adapter STL 3D file ⌀95 mm to 110×32 mm, thickness 3 mm (📦 #10137)

1 object(s) - format STL

File in STL format of a round-to-rectangular adapter with an external diameter of ⌀95 mm and a rectangular section with internal dimensions 110×32 mm. The wall thickness is 3 mm and the overall length is 120 mm.

Parameter	Value	Unit
cylinder outer diameter	95	mm
cylinder inlet length	50	mm
rectangle internal length	110	mm
rectangle internal height	32	mm
rectangle inlet length	30	mm
offset Z	0	mm
offset Y	0	mm
total length	120	mm
thickness	3	mm
chamfer	no chamfer

Round-to-Rectangular Tube Adapter STL 3D file ⌀236 mm to 248×94 mm, thickness 3 mm (📦 #10132)

1 object(s) - format STL

Download this file in STL format of a round-to-rectangular tube adapter with an outer diameter of ⌀236 mm and a rectangular section with internal dimensions 248×94 mm. The shell thickness is 3 mm and the total length is 250 mm. A chamfer is applied on the inside of the rectangular end to ease insertion.

Parameter	Value	Unit
cylinder outer diameter	236	mm
cylinder inlet length	40	mm
rectangle internal length	248	mm
rectangle internal height	94	mm
rectangle inlet length	100	mm
offset Z	0	mm
offset Y	0	mm
total length	250	mm
thickness	3	mm
chamfer	chamfer on t...

Round-to-Rectangular Tube Adapter STL file ⌀150 mm to 240×120 mm, thickness 3 mm (📦 #10091)

1 object(s) - format STL

3D model in STL format of a round-to-rectangular adapter with an outer diameter of ⌀150 mm and a rectangular section with inner dimensions 240×120 mm. The shell thickness is 3 mm and the overall length is 220 mm. A chamfer is applied on the outside of the cylindrical end to ease insertion.

Parameter	Value	Unit
cylinder outer diameter	150	mm
cylinder inlet length	25	mm
rectangle internal length	240	mm
rectangle internal height	120	mm
rectangle inlet length	25	mm
offset Z	0	mm
offset Y	0	mm
total length	220	mm
thickness	3	mm
chamfer	chamfer on t...

Round-to-Rectangular Tube Adapter STL 3D file ⌀99.7 mm to 152.5×52.5 mm, thickness 2 mm (📦 #10080)

1 object(s) - format STL

Download this 3D file in STL format of a round-to-rectangular tube adapter with an external diameter of ⌀99.7 mm and a rectangular section with internal dimensions 152.5×52.5 mm. The wall thickness is 2 mm and the overall length is 225 mm. Chamfers are applied on the outside of the cylindrical end and on the inside of the rectangular end.

Parameter	Value	Unit
cylinder outer diameter	99.7	mm
cylinder inlet length	35	mm
rectangle internal length	152.5	mm
rectangle internal height	52.5	mm
rectangle inlet length	55	mm
offset Z	0	mm
offset Y	0	mm
total length	225	mm
thickness	2	mm
chamfer	chamfers on ...

Round-to-Rectangular Tube Adapter STL file ⌀100 mm to 50×200 mm, thickness 3 mm + offset (📦 #10064)

1 object(s) - format STL

3D model in STL format of a round-to-rectangular tube adapter with an outer diameter of ⌀100 mm and a rectangular section with internal dimensions 50×200 mm. The shell thickness is 3 mm and the overall length is 200 mm. The adapter has an offset of 35 mm along the Y axis.

Parameter	Value	Unit
cylinder outer diameter	100	mm
cylinder inlet length	50	mm
rectangle internal length	50	mm
rectangle internal height	200	mm
rectangle inlet length	50	mm
offset Z	0	mm
offset Y	35	mm
total length	200	mm
thickness	3	mm
chamfer	no chamfer

Round-to-Rectangular Tube Adapter STL 3D file ⌀100 mm to 50×200 mm, thickness 3 mm (📦 #10061)

1 object(s) - format STL

Model in STL format of a round-to-rectangular adapter with an external diameter of ⌀100 mm and a rectangular section with internal dimensions 50×200 mm. The shell thickness is 3 mm and the overall length is 150 mm.

Parameter	Value	Unit
cylinder outer diameter	100	mm
cylinder inlet length	50	mm
rectangle internal length	50	mm
rectangle internal height	200	mm
rectangle inlet length	50	mm
offset Z	0	mm
offset Y	0	mm
total length	150	mm
thickness	3	mm
chamfer	no chamfer

Round-to-Rectangular Tube Adapter STL 3D file ⌀150 mm to 240×120 mm, thickness 3 mm (📦 #10053)

1 object(s) - format STL

Download this 3D model in STL format of a round-to-rectangular adapter with an external diameter of ⌀150 mm and a rectangular section with internal dimensions 240×120 mm. The shell thickness is 3 mm and the total length is 220 mm. A chamfer is present on the outside of the cylindrical end.

Parameter	Value	Unit
cylinder outer diameter	150	mm
cylinder inlet length	50	mm
rectangle internal length	240	mm
rectangle internal height	120	mm
rectangle inlet length	100	mm
offset Z	0	mm
offset Y	0	mm
total length	220	mm
thickness	3	mm
chamfer	chamfer on t...

Round-to-Rectangular Tube Adapter STL file ⌀96 mm to 67×58 mm, thickness 3 mm (📦 #10040)

1 object(s) - format STL

Download this 3D file in STL format of a round-to-rectangular tube adapter with an external diameter of ⌀96 mm and a rectangular section with internal dimensions 67×58 mm. The shell thickness is 3 mm and the overall length is 70 mm.

Parameter	Value	Unit
cylinder outer diameter	96	mm
cylinder inlet length	18	mm
rectangle internal length	67	mm
rectangle internal height	58	mm
rectangle inlet length	32	mm
offset Z	0	mm
offset Y	0	mm
total length	70	mm
thickness	3	mm
chamfer	no chamfer

Round-to-Rectangular Tube Adapter STL file ⌀96 mm to 70×61 mm, thickness 3 mm (📦 #10038)

1 object(s) - format STL

Download this 3D model in STL format of a round-to-rectangular adapter with an external diameter of ⌀96 mm and a rectangular section with inner dimensions 70×61 mm. The shell thickness is 3 mm and the overall length is 50 mm.

Parameter	Value	Unit
cylinder outer diameter	96	mm
cylinder inlet length	18	mm
rectangle internal length	70	mm
rectangle internal height	61	mm
rectangle inlet length	12	mm
offset Z	0	mm
offset Y	0	mm
total length	50	mm
thickness	3	mm
chamfer	no chamfer

Round-to-Rectangular Tube Adapter STL file ⌀99 mm to 77×70 mm, thickness 3 mm (📦 #10036)

1 object(s) - format STL

Download this model in STL format of a round-to-rectangular tube adapter with an outer diameter of ⌀99 mm and a rectangular section with internal dimensions 77×70 mm. The shell thickness is 3 mm and the total length is 50 mm.

Parameter	Value	Unit
cylinder outer diameter	99	mm
cylinder inlet length	18	mm
rectangle internal length	77	mm
rectangle internal height	70	mm
rectangle inlet length	12	mm
offset Z	0	mm
offset Y	0	mm
total length	50	mm
thickness	3	mm
chamfer	no chamfer

Round-to-Rectangular Tube Adapter STL file ⌀94 mm to 77×70 mm, thickness 4 mm (📦 #10035)

1 object(s) - format STL

Download this 3D file in STL format of a round-to-rectangular adapter with an external diameter of ⌀94 mm and a rectangular section with inner dimensions 77×70 mm. The shell thickness is 4 mm and the overall length is 50 mm.

Parameter	Value	Unit
cylinder outer diameter	94	mm
cylinder inlet length	18	mm
rectangle internal length	77	mm
rectangle internal height	70	mm
rectangle inlet length	12	mm
offset Z	0	mm
offset Y	0	mm
total length	50	mm
thickness	4	mm
chamfer	no chamfer

Round-to-Rectangular Tube Adapter STL 3D file ⌀120 mm to 148×78 mm, thickness 2 mm (📦 #9946)

1 object(s) - format STL

File in STL format of a round-to-rectangular adapter with an outer diameter of ⌀120 mm and a rectangular section with internal dimensions 148×78 mm. The shell thickness is 2 mm and the overall length is 70 mm.

Parameter	Value	Unit
cylinder outer diameter	120	mm
cylinder inlet length	25	mm
rectangle internal length	148	mm
rectangle internal height	78	mm
rectangle inlet length	25	mm
offset Z	0	mm
offset Y	0	mm
total length	70	mm
thickness	2	mm
chamfer	no chamfer

Round-to-Rectangular Tube Adapter STL file ⌀65 mm to 65×120 mm, thickness 3 mm (📦 #9910)

1 object(s) - format STL

Download this file in STL format of a round-to-rectangular tube adapter with an outer diameter of ⌀65 mm and a rectangular section with inner dimensions 65×120 mm. The shell thickness is 3 mm and the total length is 50 mm.

Parameter	Value	Unit
cylinder outer diameter	65	mm
cylinder inlet length	5	mm
rectangle internal length	65	mm
rectangle internal height	120	mm
rectangle inlet length	10	mm
offset Z	0	mm
offset Y	0	mm
total length	50	mm
thickness	3	mm
chamfer	no chamfer

Round-to-Rectangular Tube Adapter STL file ⌀75 mm to 121×70 mm, thickness 3 mm (📦 #9904)

1 object(s) - format STL

Download this 3D file in STL format of a round-to-rectangular tube adapter with an outer diameter of ⌀75 mm and a rectangular section with inner dimensions 121×70 mm. The wall thickness is 3 mm and the total length is 150 mm.

Parameter	Value	Unit
cylinder outer diameter	75	mm
cylinder inlet length	20	mm
rectangle internal length	121	mm
rectangle internal height	70	mm
rectangle inlet length	30	mm
offset Z	0	mm
offset Y	0	mm
total length	150	mm
thickness	3	mm
chamfer	no chamfer

Round-to-Rectangular Tube Adapter STL file ⌀32 mm to 37×24 mm, thickness 2 mm (📦 #9897)

1 object(s) - format STL

3D model in STL format of a round-to-rectangular tube adapter with an outer diameter of ⌀32 mm and a rectangular section with internal dimensions 37×24 mm. The wall thickness is 2 mm and the total length is 56 mm.

Parameter	Value	Unit
cylinder outer diameter	32	mm
cylinder inlet length	27	mm
rectangle internal length	37	mm
rectangle internal height	24	mm
rectangle inlet length	9	mm
offset Z	0	mm
offset Y	0	mm
total length	56	mm
thickness	2	mm
chamfer	no chamfer

Round-to-Rectangular Tube Adapter STL file ⌀149.6 mm to 120×150 mm, thickness 3 mm (📦 #9894)

1 object(s) - format STL

Download this model in STL format of a round-to-rectangular adapter with an external diameter of ⌀149.6 mm and a rectangular section with inner dimensions 120×150 mm. The wall thickness is 3 mm and the overall length is 200 mm. A chamfer is present on the inside of the rectangular end to ease insertion.

Parameter	Value	Unit
cylinder outer diameter	149.6	mm
cylinder inlet length	35	mm
rectangle internal length	120	mm
rectangle internal height	150	mm
rectangle inlet length	30	mm
offset Z	0	mm
offset Y	0	mm
total length	200	mm
thickness	3	mm
chamfer	chamfer on t...

Round-to-Rectangular Tube Adapter STL 3D file ⌀150 mm to 256×44 mm, thickness 3 mm + offset (📦 #9890)

1 object(s) - format STL

Download this file in STL format of a round-to-rectangular adapter with an outer diameter of ⌀150 mm and a rectangular section with inner dimensions 256×44 mm. The shell thickness is 3 mm and the total length is 200 mm. The adapter has an offset of 10 mm along the Z axis.

Parameter	Value	Unit
cylinder outer diameter	150	mm
cylinder inlet length	55	mm
rectangle internal length	256	mm
rectangle internal height	44	mm
rectangle inlet length	30	mm
offset Z	10	mm
offset Y	0	mm
total length	200	mm
thickness	3	mm
chamfer	no chamfer

Round-to-Rectangular Tube Adapter STL file ⌀150 mm to 300×45 mm, thickness 3 mm + offset (📦 #9888)

1 object(s) - format STL

Download this 3D file in STL format of a round-to-rectangular tube adapter with an external diameter of ⌀150 mm and a rectangular section with internal dimensions 300×45 mm. The shell thickness is 3 mm and the overall length is 200 mm. The adapter has an offset of 60 mm along the Z axis.

Parameter	Value	Unit
cylinder outer diameter	150	mm
cylinder inlet length	30	mm
rectangle internal length	300	mm
rectangle internal height	45	mm
rectangle inlet length	30	mm
offset Z	60	mm
offset Y	0	mm
total length	200	mm
thickness	3	mm
chamfer	no chamfer

Round-to-Rectangular Tube Adapter STL file ⌀71 mm to 122×72 mm, thickness 3 mm (📦 #9884)

1 object(s) - format STL

File in STL format of a round-to-rectangular tube adapter with an outer diameter of ⌀71 mm and a rectangular section with inner dimensions 122×72 mm. The wall thickness is 3 mm and the total length is 150 mm.

Parameter	Value	Unit
cylinder outer diameter	71	mm
cylinder inlet length	20	mm
rectangle internal length	122	mm
rectangle internal height	72	mm
rectangle inlet length	30	mm
offset Z	0	mm
offset Y	0	mm
total length	150	mm
thickness	3	mm
chamfer	no chamfer

Round-to-Rectangular Tube Adapter STL file ⌀68 mm to 122×72 mm, thickness 3 mm (📦 #9883)

1 object(s) - format STL

3D model in STL format of a round-to-rectangular tube adapter with an external diameter of ⌀68 mm and a rectangular section with internal dimensions 122×72 mm. The wall thickness is 3 mm and the total length is 150 mm.

Parameter	Value	Unit
cylinder outer diameter	68	mm
cylinder inlet length	20	mm
rectangle internal length	122	mm
rectangle internal height	72	mm
rectangle inlet length	30	mm
offset Z	0	mm
offset Y	0	mm
total length	150	mm
thickness	3	mm
chamfer	no chamfer

Round-to-Rectangular Tube Adapter STL file ⌀73 mm to 122×72 mm, thickness 3 mm (📦 #9882)

1 object(s) - format STL

Download this 3D file in STL format of a round-to-rectangular tube adapter with an external diameter of ⌀73 mm and a rectangular section with inner dimensions 122×72 mm. The shell thickness is 3 mm and the total length is 150 mm.

Parameter	Value	Unit
cylinder outer diameter	73	mm
cylinder inlet length	20	mm
rectangle internal length	122	mm
rectangle internal height	72	mm
rectangle inlet length	30	mm
offset Z	0	mm
offset Y	0	mm
total length	150	mm
thickness	3	mm
chamfer	no chamfer

Round-to-Rectangular Tube Adapter STL file ⌀75 mm to 122×72 mm, thickness 3 mm (📦 #9880)

1 object(s) - format STL

3D file in STL format of a round-to-rectangular tube adapter with an external diameter of ⌀75 mm and a rectangular section with internal dimensions 122×72 mm. The wall thickness is 3 mm and the total length is 150 mm.

Parameter	Value	Unit
cylinder outer diameter	75	mm
cylinder inlet length	19	mm
rectangle internal length	122	mm
rectangle internal height	72	mm
rectangle inlet length	30	mm
offset Z	0	mm
offset Y	0	mm
total length	150	mm
thickness	3	mm
chamfer	no chamfer

Round-to-Rectangular Tube Adapter STL file ⌀122 mm to 240×270 mm, thickness 3 mm (📦 #9869)

1 object(s) - format STL

Download this 3D file in STL format of a round-to-rectangular adapter with an outer diameter of ⌀122 mm and a rectangular section with internal dimensions 240×270 mm. The wall thickness is 3 mm and the overall length is 60 mm. A chamfer is applied on the outside of the cylindrical end.

Parameter	Value	Unit
cylinder outer diameter	122	mm
cylinder inlet length	10	mm
rectangle internal length	240	mm
rectangle internal height	270	mm
rectangle inlet length	5	mm
offset Z	0	mm
offset Y	0	mm
total length	60	mm
thickness	3	mm
chamfer	chamfer on t...

Round-to-Rectangular Tube Adapter STL file ⌀123 mm to 240×270 mm, thickness 3 mm (📦 #9868)

1 object(s) - format STL

Download this model in STL format of a round-to-rectangular tube adapter with an outer diameter of ⌀123 mm and a rectangular section with internal dimensions 240×270 mm. The shell thickness is 3 mm and the total length is 55 mm. A chamfer is applied on the outside of the cylindrical end to ease insertion.

Parameter	Value	Unit
cylinder outer diameter	123	mm
cylinder inlet length	10	mm
rectangle internal length	240	mm
rectangle internal height	270	mm
rectangle inlet length	5	mm
offset Z	0	mm
offset Y	0	mm
total length	55	mm
thickness	3	mm
chamfer	chamfer on t...

Round-to-Rectangular Tube Adapter STL 3D file ⌀154 mm to 146×136 mm, thickness 2 mm (📦 #9867)

1 object(s) - format STL

Download this 3D file in STL format of a round-to-rectangular tube adapter with an outer diameter of ⌀154 mm and a rectangular section with inner dimensions 146×136 mm. The shell thickness is 2 mm and the total length is 50 mm.

Parameter	Value	Unit
cylinder outer diameter	154	mm
cylinder inlet length	20	mm
rectangle internal length	146	mm
rectangle internal height	136	mm
rectangle inlet length	5	mm
offset Z	0	mm
offset Y	0	mm
total length	50	mm
thickness	2	mm
chamfer	no chamfer

Round-to-Rectangular Tube Adapter STL 3D file ⌀155 mm to 144×127 mm, thickness 3 mm (📦 #9857)

1 object(s) - format STL

Download this file in STL format of a round-to-rectangular adapter with an outer diameter of ⌀155 mm and a rectangular section with internal dimensions 144×127 mm. The shell thickness is 3 mm and the total length is 108 mm.

Parameter	Value	Unit
cylinder outer diameter	155	mm
cylinder inlet length	30	mm
rectangle internal length	144	mm
rectangle internal height	127	mm
rectangle inlet length	57	mm
offset Z	0	mm
offset Y	0	mm
total length	108	mm
thickness	3	mm
chamfer	no chamfer

Use cases for round-to-rectangular tube adapters

Round-to-rectangular adapters make it possible to connect two ducts of different shapes, ensuring a controlled transition between a cylindrical inlet and a rectangular or square outlet. 3D-printable, they can be used for both air and liquid flow in ventilation, transfer, or duct adjustment projects. Their parametric design allows precise definition of dimensions, lengths, and possible offsets for a configuration-specific fit.

The parametric generation system also makes it possible to create adapters where the circular inlet section is massive compared to the much smaller outlet, meeting specific connection requirements. This is the case with this geometry-evolving adapter, which provides a stable transition between very different sections without abrupt flow disruption.

When an offset between axes is required, an offset adapter allows adjustment of duct positioning while maintaining consistent wall thickness and a clean fit. This type of model simplifies assembly in setups where alignment is not perfect or requires slight mechanical offset.

Finally, a 80mm cylinder-to-80x80mm square adapter illustrates a more standard case: a simple conversion between a round tube and a square outlet, without offset. These 3D-printable adapters stand out for their precision and design flexibility, suitable for many technical connection applications.