Historically, most producers raised every heifer born. However, advancements in transition and reproductive management, coupled with widespread use of sex-sorted semen in dairy heifers and cows, have led to an oversupply of dairy replacement heifers in the US In addition to be a large negative cash flow, raising costs are significantly higher than replacement values, resulting in large economic losses, assuming market values fail to recover quickly. Consequently, producers are asking “How many heifers do I need?” and “What do I do with the excess?” Future herd turnover is the driver of replacement needs. To calculate herd turnover, divide the total number of cows (milking and dry) that leave the herd (sold or dead) over 12 mo by the average population at risk (milking and dry) for that same time. Assuming a stable herd size, cows removed due to mortality, disease, infertility, low milk production, or sold for dairy purposes should be replaced immediately with fresh heifers to keep facilities full and more completely dilute fixed costs. Historic farm-level herd turnover risks are a logical starting point for predicting replacement needs but cannot account for unanticipated health, fertility problems, or economic opportunities to improve the herd. Herd turnover is costly, but limiting the number of replacement heifers raised may lead to large future lost opportunity costs due to an inability or unwillingness to replace a less productive cow at the appropriate time. Aside from the anticipated herd turnover, other considerations, beginning at the time of conception, include sire choice, abortion risk, stillbirth risk, heifer mortality risk, heifer reproductive efficiency, heifer abortion risk, and heifer growth rate. Producers are now breeding some of their dairy animals to beef sires and culling excess heifers at various ages, depending on the anticipated market values. Criteria for culling include genetic potential, growth performance, and health history. Proper and timely culling decisions can reduce the cash flow drain, lower future economic loss, and increase the net value of heifers entering the milking herd.