Modern mobile phones have a powerful processing unit that can perform multiple operations simultaneously. But the main constrain is the processing power and energy required to drive it. Cloud computing has come as a blessing for the mobile computing as it possesses a vast resource, high storage capacity and high processing power. In Mobile Cloud Computing (MCC), computation is offloaded to the cloud, cloud processes the data and generates information; and sends it back to the mobile device. Probability of offloading depends on line bandwidth, line length, size of data, processing speed of mobile, processing speed of cloud, storage and energy capacity of mobile etc. This paper presents a model for efficient data offloading decision, depending on the total execution time of a task when the data computation happens in the mobile and when it is offloaded to the cloud. An algorithm has been proposed here on data offloading decision. As thus an equation has been proposed to observe the probability of offloading process.