: Interval arithmetic is a method for performing computations on measurements that are only known to within a xed error range. As the measurements are combined mathematically, their error intervals are also combined, in a conservative fashion. While the technique of interval analysis has found uses in many areas of computing in recent years, it has not yet been applied heavily in computer vision. We describe the technique of interval arithmetic and show how its use can lead to a greater understanding of depth from stereo estimates.