Summary The experimental investigation of the melting behavior of a phase change material (PCM) inside a spherical container is reported. PCM considered for the study is lauric acid whose melting point is about 43°C. Unconstrained melting experiments are carried out at two different temperatures, ie, at 60°C and 80°C. The initial temperature of the PCM is taken as 30°C. To carry out a detailed analysis of the heat transfer, the transient variations in the melt fraction and amount of energy stored are derived. In order to estimate the liquid/solid volumes, a novel image processing technique is developed. In this approach, a circle‐fitting algorithm is employed to obtain the amount of PCM melted inside a spherical container. The total instantaneous amount of heat transport to the PCM is measured with an uncertainty of about 6.1%. The results obtained by the introduced circle‐fitting algorithm have been compared qualitatively and quantitatively with the solid modeling method. The present technique could capture the asymmetric behavior of the solid PCM. The experimental findings show that the rate of melt fraction is high at the beginning of the experiment due to a larger area of contact between the spherical container and solid PCM. Further, parametric analysis has been performed and reported in terms of Fourier, Stefan, and Grashof numbers.