Milligram-scale Flame Calorimetry (MFC) is a controlled-atmosphere flammability technique used to screen fire retardant materials which do not intumesce. The MFC is a desirable technique due to its calorimetry capabilities, small sample size requirement and allowance for the non-intrusive study of an axisymmetric laminar diffusion flame. In in this work, a new MFC pyrolyzer system was developed to emulate the burning behavior of cone calorimetry samples, improving upon the limited use of the MFC. The new pyrolyzer system enables the testing of 30 – 55 mg samples as well as intumescent charring materials. The material surface temperature is directly measured during a test, which was previously not possible. A comparative study of five representative materials, covering a wide range of sooting and charring conditions, is conducted considering the new MFC, along with Microscale Combustion Calorimetry and cone calorimetry. It is concluded that the new MFC can be used to rank flammability of a wide range of polymeric materials and this ranking is the same at that obtained through cone calorimetry testing.