In this paper, the buoyancy-controlled jet flames from the inclined rectangular nozzles with different aspect ratios have been investigated. The length-to-width aspect ratios of nozzles are 1, 2.25, 4, 9, and 16 with the same cross-sectional area. The inclined angles of the nozzle to the horizontal direction are 0 degrees, 30 degrees, 60 degrees, and 90 degrees. The value of flame length changes at the same inclined angle for different aspect ratios. A correlation has been developed to calculate the flame length of jet flame for different inclined nozzle and aspect ratios with an arbitrary angle.