Abstract: Automated brain tumor detection and tumor area calculation is a challenging task due to the complex structure of brain. MRI images offer better difference concern of various soft tissues of human body.MRI Imaging play an important role in brain tumor for detection analysis, diagnosis and treatment planning. It helpful to doctor for detection of tumor and diagnosis of disease as well as treatment planning of brain tumor. Brain tumor is an abnormal growth of cell of brain. MRI Image provides better results than CT, Ultrasound, and X-ray.In this study, design and developed Matlab application using various preprocessing, post processing and methods like; (Filtering, contrast enhancement, Edge detection) and post processing techniques like; (Histogram, Threshold, Segmentation, Morphological operation) through image processing (IP) tool. The brain tumor segmentation carried manually from MRI images is very crucial and time consuming task. Therefore, to avoid that, it needs to use computer aided method for detection of brain tumor. In this application MRI image is taken as input and applied various image processing techniques step by step upto brain tumor is separated from MRI images and tumor area is calculated in MM2. Keywords: Brain tumor, MRI-Images, Tumor area, image processing.