NPK Calculator is an Android app developed by Anton Simonov that optimizes the ratio of macronutrients and micronutrients in fertilizer solutions for use in hydroponics or soil. The app is designed to ensure optimal growth of living beings such as plants by providing a proper balance of essential nutrients and trace nutrients. It also prevents nutrient lock-out, which can occur when the pH is out of balance or when there is too much of a nutrient. The app includes an extensive in-app database of simple and complex fertilizers available in the market. Additionally, several nutrition programs created by knowledgeable growers with long-term experience are available in preset tabs.

The NPK Calculator app is an excellent tool for anyone looking to ensure optimal growth of their plants. It is easy to use and provides a precise nutrient balance to prevent nutrient lock-out. The app's in-app database of fertilizers is extensive, and the preset tabs with nutrition programs by knowledgeable growers provide an added convenience. Overall, NPK Calculator is a must-have app for anyone interested in hydroponics or soil-based plant growth.