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Liner Sizing Guides

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.

Liner Sizing Guides

The standard 10-1 ratio has been used in the chart below. 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.
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
1,357-1846 sq. in.
requires
16” liner

Sizing Chart

Calculate the area needed for fireplace liners of various shapes:

Rectangle

  • Figure the opening for the fireplace (length x width)
  • Divide by 12

Square

  • Area = length x width

Triangle

  • Area = (length x width) x 1/2
Original Liner Diameter
  6 7 8 9 10 11 12 13 1416 18
4.56.08.010.011.513.515.017.019.0   
5.05.57.59.511.013.014.516.518.520.023.5 
5.5 7.09.010.512.514.016.018.019.523.0 
6.0 6.58.510.012.013.515.517.519.022.5 
6.5  8.09.511.513.015.017.018.522.0 
7.0  7.59.011.012.514.516.518.5 21.5 
7.5   8.510.512.014.016.017.521.0  
8.0   8.010.011.513.515.517.020.524.0
8.5    9.511.013.015.016.520.023.5
9.0    9.010.512.514.516.019.523.0
9.5     10.012.014.015.519.022.5
10.0     10.011.513.515.018.522.0
10.5      11.013.014.518.021.5
11.0       12.513.517.521.0
11.5       12.013.017.020.5
12.0        12.516.520.0
12.5         16.019.5
13.0         15.519.0
13.5         14.518.5
14.0          18.0
14.5          17.5
15.0          17.0
15.0          16.5
15.0          16.0

Circular Sizing Chart

Calculate the area needed for fireplace liners of circular shapes:

Circle

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

  • 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 of the oval

  •   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