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Calcimator

Fireplace & Chimney Calculator

Size a chimney flue based on the 10:1 fireplace-to-flue area ratio and estimate draft pressure.

Inputs

in
in
ft

Results

Required Flue Area

100.8 sq in

Flue Size

10.04 in

Fireplace Opening Area1,008 sq in
Min Chimney Height20 ft
Estimated Draft Pressure0 in w.c.
How to Use This Calculator
  1. Enter the fireplace opening width and height in inches.
  2. Input the chimney height in feet (measured from the firebox floor to the top of the flue).
  3. Select the flue shape (round or rectangular) and material.
  4. Review the minimum flue area, throat dimensions, and smoke chamber height.
  5. Verify design compliance with NFPA 211 and local building codes.
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