Accurately estimating software size, cost, effort, and schedule is probably the biggest challenge facing software developers today. Traditional intuitive estimation methods have consistently produced optimistic results which contribute to the too familiar cost overrun and schedule slippage. It is observed that different methods give different results for the same inputs because many intangible of historical data and every software project will have its own unique features and cannot be compared with future projects. Experts suggest using more than one estimation method and analyzing the results before making a decision. An accurate estimate of software size is an essential element in the calculation of estimated project costs and schedules. In this paper we have taken different projects and estimate their effort using various models. We also used fuzzy logic approach.We also done its implementation.