The process of determining the vitamin C content in fruits is complex and expensive. The aim of the study is to measure the amount of vitamin C in fruit with a simple colorimeter, cheaply and with high reliability. The designed colorimeter and the method used are important in terms of transforming theoretical knowledge into practice by using it in schools and skill workshops that implement STEAM. Equipped with colorimeter, color sensor and photodiode. The value of the blue, red and green colors measured by the colorimeter within the specified range is displayed on the LED screen. With the use of vitamin C diluted with DCPIP, the solution gradually becomes colorless and is measured with a colorimeter. The variation in output voltage determines the vitamin C concentration of the different aqueous solutions to be tested. Experimental results show that it is possible to measure the amount of vitamin C in fruits with a simple colorimeter. Trying to avoid fruit pulp in the measurement process shows that the measurement process will reach more accurate results.