Cantilever-based sensors, though commonly used in atomic force microscopy, have found novel applications in numerous sensing applications including temperature, humidity, and mass measurements. In this numerical study, the effect of three different cantilever lengths immersed in three different fluids on their vibration properties is investigated using finite element analysis. The cantilever is made of steel and is immersed in crude oil, water, and glycerol for different lengths. Results indicate a direct relationship between the increased dipping length and reduced deflection, along with a consistent decrease in resonant frequency. The findings can help predict density estimations of unknown fluids.