A contact angle measurement system includes a housing that can hold a volume of a first fluid having a first density, an adjustable rock sample holder positioned within the housing, a fluid dropper attached to the housing, an image capturing a device, and a computer system. The holder can support a rock sample. An orientation of the holder relative to the housing is adjustable such that an outer surface of the rock sample is at a non-zero angle relative to a lower wall of the housing. When the orientation of the holder relative to the housing is such that the outer surface of the rock sample is at the non-zero angle relative to the lower wall, the fluid droplet traverses the outer surface of the rock sample. The image capturing device can capture images of the fluid droplet as the fluid droplet traverses the outer surface of the rock sample.