The value of old milk bottles depends on a number of factors including shape, condition and rarity. The LoveToKnow and Collectors Weekly websites provide photographs and general guidelines to help determine value.
The shape of the milk bottle is used to establish its age. Round bottles were made in the 1930s or earlier. A square bottom and shorter sides place the bottle in the 1940s or later. Chips, cracks and excessive wear reduce value. Rare bottles are worth more money. White or green milk glass and glass lids are among characteristics of rare bottles as described by Collectors Weekly. Seeking a professional appraisal is one way to weed out reproductions.