Internet of Things (IoT) is a revolutionary technology by creating smart surroundings that make it easier for humans to do their work. The IoT applications can be found in many fields such as logistics, transportation, healthcare, industries, supply chain and agriculture. In the agriculture sector, farmers use the traditional method for irrigation purposes. The farmers have no special idea about when and how much water is required for crops due to which the crops production is reduced. However, the low intensity of light also reduces the crops production. Also, water scarcity is now a widespread issue that affects many nations, particularly in rural and arid regions. Therefore, this necessitates the need for fabricating IoT based smart irrigation system to optimize water usage and monitor agriculture. This paper proposes a robust framework for smart irrigation systems. It is based on water meter using mathematical models to estimate the required water rate and effectively control it. The mathematical model is integrated into the Arduino microcontroller to check the level of soil moisture and light intensity and to compare it with the predefined threshold value. The proposed system enhances the effectiveness of watering systems by increasing crop production and consuming less water by more than 80%.