Human Activity Tracker for Health Monitoring System (HATHMS) is a web-based system which developed for elderly people so they able to know their daily activity with detail information. Metabolic equivalent of task (MET score) is used in HATHMS so the user able to differentiate the activity to light, moderate and vigorous activity with MET score. By using MET score, calories burned of each activity can be calculated and elderly people can prevent undergo vigorous activity. The system is a low-cost web-based system and developed by using Django web framework. The system uses wearable device to detect the physical activities of the elderly people and send the information to a single board computer (Raspberry Pi) to measure the level of daily activity of the user. Based on the detected activity, the data is retrieved from database to analyse and convert it to information in the form of graph. The information includes total time used for each activity, activity level of user, calories burned calculation and weight loss calculation. Based on the activity level of user in that day, HATHMS will give some suggestions and recommendation to user if the activity level is low. HATHMS contains two type of user which is normal user (elderly people) and the caregiver. Caregiver can check all the information about the normal user who under his supervision. If the normal user undergoes abnormal activity like sitting, lying or do vigorous activity for too long, HATHMS will detect the abnormal activity and send an email notification to the normal user and his caregiver.