A system and method for estimating livestock weight is described. Embodiments of the system can include a computing device and a three-dimensional tag configured to be secured to an animal. One or more images of an animal, including the three-dimensional tag, can be processed to take various measurements of the animal. A scaling factor for the measurements can be based on the three-dimensional tag. After the measurement are calibrated, a weight of the animal can be estimated based on the calibrated measurements.