2147C Fletcher Ave Indianapolis, IN, 46203   800.897.8481   317.636.0751
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Liner Sizing Guides

Below are a sample of forms and tables which you can find in our catalog to help get you started. But if you still have questions. No worries. Just call us at 800.897.8481, and Customer Service will connect you with our Technical Support Team.
Fireplace Opening and Liner Size
Up to 600 sq. in. requires 9" liner
601-760 sq. in. requires 10" liner
761-942 sq. in. requires 11" liner
943-1,140 sq. in. requires 12" liner
1,141-1,356 sq. in. requires 14" liner
1,356-1,846 sq. in. requires 16" liner
The standard 10-1 ratio has been used in the chart above. To be safe, we recommend a 10-1 ratio for chimneys less than or equal to 25 feet in height and a 12-1 ratio for chimneys greater than 25 feet in height.

Rectangle Sizing Chart

Click below to calculate the area needed for fireplace liners of various shapes:

Figure the opening for the fireplace
Area = length x width ÷ 12

Figure the opening for the fireplace
Area = length x width

Figure the opening for the fireplace
Area = (length x width) x 1/2

Original Liner Diameter
6 7 8 9 10 11 12 13 14 16 18
4.5 6.0 8.0 10.0 11.5 13.5 15.0 17.0 19.0
5.0 5.5 7.5 9.5 11.0 13.0 14.5 16.5 18.5 20.0 23.5
5.5 7.0 9.0 10.5 12.5 14.0 16.0 18.0 19.5 23.0
6.0 6.5 8.5 10.0 12.0 13.5 15.5 17.5 19.0 22.5
6.5 8.0 9.5 11.5 13.0 15.0 17.0 18.5 22.0
7.0 7.5 9.0 11.0 12.5 14.5 16.5 18.5 21.5
7.5 8.5 10.5 12.0 14.0 16.0 17.5 21.0
8.0 8.0 10.0 11.5 13.5 15.5 17.0 20.5 24.0
8.5 9.5 11.0 13.0 15.0 16.5 20.0 23.5
9.0 9.0 10.5 12.5 14.5 16.0 19.5 23.0
9.5 10.0 12.0 14.0 15.5 19.0 22.5
10.0 10.0 11.5 13.5 15.0 18.5 22.0
10.5 11.0 13.0 14.5 18.0 21.5
11.0 12.5 13.5 17.5 21.0
11.5 12.0 13.0 17.0 20.5
12.0 12.5 16.5 20.0
12.5 16.0 19.5
13.0 15.5 19.0
13.5 14.5 18.5
14.0 18.0
14.5 17.5
15.0 17.0
15.0 16.5
15.0 16.0

Circular Sizing Chart

Click below to calculate the area needed for fireplace liners of circular shapes:

Area = π r2
Circumference = π d
π = 3.14
r = radius (half of diameter)
r2 = radius squared
d = diameter

Area = Rectangle+Circle
Divide the shape into a rectangle and two half circles
(1/2 circle on each end of the rectangle)
Figure the area for the rectangle
Then figure the area for the circle
Add the two areas together to get the approximate area

4" 5" 6" 7" 8" 9" 10" 11"
12"
in²=113.14
17.3"
79
16.75"
86
16"
93
15.5"
99
14.25"
102
13.5"
106
11"
in²=94.99
16.1"
65
15.5"
72
15"
78
14.1"
73
13.5"
87
12.6"
92
10"
in²=78.50
16"
50
15"
57
14"
63
13.25"
68
12"
72
11.3"
76
9"
in²=63.58
13.1"
43
12.5"
50
12"
53
11.1"
56
10.4"
61
8"
in²=50.25
11.6"
36
11"
42
10.3"
45
9.5"
48
7"
in²=38.46
10"
36
9.2"
42
8.3"
45
6"
in²=28.26
8.1"
24
7.4"
25
Stainless Steel M-Flex .006” & .005” Light Wall, M-Flex Smoothwall, Premier Flex Rigid, and Premier Flex Heavy Wall (304 & 316) have a lifetime transferrable warranty. In order for the warranty to be valid, the liner must be maintained by a chimney professional.

M-Flex Aluminum Liner has a 25-year transferrable warranty. In order for the warranty to be valid, the liner must be maintained by a chimney professional. Call us today 1-800-897-8481 for your technical needs.