DUCT EQUIVALENT CHART
Duct Piece
Smooth, straight
3¼" x 10"
(83 mm x 254 mm)
straight
3¼" x 14"
(83 mm x 356 mm)
straight
90° Elbow , round
45° Elbow , round
3¼" x 10"
(83 mm x 254 mm),
90° Elbow , round
3¼" x 10"
(83 mm x 254 mm),
45° Elbow , round
3¼" x 10"
(83 mm x 254 mm),
Flat elbow
3¼" x 10"
(83 mm x 254 mm)
to round
Round to 3¼" x 10"
(83 mm x 254 mm)
90° Elbow
English 10
Equivalent
Size
Length
(in./mm)
(ft/m)
6 (152)
1.2 (0.37)
8 (203)
0.7 (0.21)
10 (254)
0.6 (0.18)
N/A
1 (0.3)
N/A
0.7 (0.21)
6 (152)
12 (3.7)
8 (203)
6 (1.8)
10 (254)
5 (1.5)
6 (152)
5 (1.5)
8 (203)
3 (0.9)
10 (254)
2 (0.6)
N/A
5 (1.5)
N/A
15 (4.6)
N/A
20 (6.1)
6 (152)
5 (1.5)
8 (203)
2 (0.6)
6 (152)
10 (3)
Duct Piece
3¼" x 10" (83 mm x 254 mm)
to round 90° Elbow
3¼" x 10" (83 mm x 254 mm)
Center reverse elbow , left
3¼" x 10" (83 mm x 254 mm),
Center reverse elbow , right
3¼" x 10" (83 mm x 254 mm),
Left reverse elbow
3¼" x 10" (83 mm x 254 mm),
Right reverse elbow
Round wall cap
Round roof cap
2" (51 mm) long, 3¼" x 10"
(83 mm x 254 mm) flex
3¼" x 10" (83 mm x 254 mm),
Roof jack and shutter
NOTE: These commonly used installation parts can be purchased at
a local hardware store.
Measurements in inches (mm).
Equivalent
Size
Length
(in./mm)
(ft/m)
6 (152)
10 (3)
N/A
15 (4.6)
N/A
25 (7.6)
N/A
15 (4.6)
N/A
25 (7.6)
6 (152)
2 (0.6)
8 (203)
2 (0.6)
10 (254)
2 (0.6)
6 (152)
2 (0.6)
2 (0.6)
8 (203)
10 (254)
2 (0.6)
N/A
20 (6.1)
N/A
2 (0.6)