FIGRA, or the Fire Growth Rate Index, is a key parameter used in SBI testing to evaluate how quickly a fire develops after ignition. It is widely applied in reaction-to-fire assessment, especially for building materials and interior products. In simple terms, FIGRA helps describe the intensity and speed of fire growth by combining heat release rate with time. A lower FIGRA value generally indicates a slower fire growth tendency, while a higher value suggests that the material may contribute more rapidly to fire development.In SBI testing, a specimen is exposed to a controlled flame source in a corner configuration. The test is designed to simulate the early stages of a fire in a room-like environment. During the test, the heat release rate is measured continuously. FIGRA is then calculated from the relationship between the peak heat release rate and the time at which it occurs, with the result reflecting how quickly the fire becomes severe. Because fire growth behavior is one of the most important factors in building safety, FIGRA is often used as a classification criterion in fire performance standards.The significance of FIGRA lies in its ability to provide a practical measure of fire spread potential. Materials with a low FIGRA are usually considered to have better fire performance because they delay flashover-like conditions and reduce the speed at which dangerous heat levels are reached. This can be especially important in occupied buildings, where slower fire growth may allow more time for evacuation and firefighting response. In contrast, a high FIGRA may indicate that the tested product contributes to rapid fire escalation, which could increase risk in real fire scenarios.FIGRA is not the only factor considered in SBI testing, but it is one of the most influential. It is commonly evaluated together with other indicators such as total heat release, smoke production, and flaming droplets or particles. These combined results provide a more complete understanding of how a material behaves under fire exposure. As a result, FIGRA plays an important role in product classification, material selection, and compliance with fire safety regulations.The use of FIGRA in SBI testing supports objective and repeatable evaluation of construction and interior products. By focusing on fire growth behavior rather than only ignition resistance, it offers a more realistic view of potential fire hazards. This makes it valuable for engineers, manufacturers, regulators, and designers who aim to improve building safety. In modern fire testing practice, FIGRA remains a central indicator for understanding the contribution of materials to fire development and for supporting safer material choices in construction and interior applications.