Steps to calculate a fireplace liner size:

Step #1: Measure the Height of your Chimney from the top crown of your chimney to the top of the smoke chamber (inside your chimney). = Height (FT)
Step #2: Measure the height and width of your Fireplace Opening (inside your home). = Height (IN) = Width (IN)
Step #3: Click on the GENERATE LINER SIZE button
square inch area liner is required. inch diameter liner is required. The calculations above are formulated by taking your answer from Step #2 and dividing it by the appropriate ratio, 10 or 12. (To be safe, we recommend a 10-1 ratio for chimneys less than 25 feet in height and a 12-1 ratio for chimneys greater than 25 feet in height.)
Area in Square Inches of ROUND Liners 3" 4" 5" 6" 7" 8" 9" 10" 11" 12" 13" 14" 16" 18" 7.07 12.56 19.63 28.26 38.46 50.25 63.58 78.5 94.99 113.14 132.66 153.86 200.96 254.34
Step #4: Measure the width and length of the chimney flue (on top of your chimney) to make sure the liner size required will fit down the flue. Also remember, WOOD applications require insulation, so keep in mind you need to have the required space to fit ½" thick TOP Wrap Insulation & Mesh around the liner or 1" of space all away around the chimney liner for our TOP Mix poured insulation. Always take into consideration any offsets or turns inside the flue. If the liner required for your fireplace opening is too large to fit down the cavity of your chimney … call our Technical Support to help determine solutions for your application. Don't see a size? Contact us … we will be glad to help! Custom or larger sizes available upon request. Phone: 877-473-3923 Email: sales@chimneylinersusa.com