Stochastic models were developed to estimate the economic impact in the first 30 d in milk of oral calcium supplementation (Bovikalc, Boehringer Ingelheim Vetmedica Inc., St. Joseph, MO) to multiparous postparturient dairy cows using 4 different strategies: 1) supplementation of cows with a high previous lactation mature equivalent milk yield, 2) supplementation of lame cows, 3) supplementation of cows that either have a high previous lactation mature equivalent milk yield or are lame, and 4) supplementation of all cows. Data from current literature was used to model input variables associated with the costs and risks related to milk production, postparturient disease, and culling. The mean net herd impact per 1,000 calvings for each of the 4 supplementation strategies was $4,425, $5,812, $8,313, and $3,065 respectively. Return on investment was 6.5 to 1 for supplementation of lame cows, 1.8 to 1 for high milk yield and lame cows, 1.1 to 1 for high milk yield cows, and 0.3 to 1 for supplementation of all multiparous postpartum cows. A herd’s average milk yield at first test had the highest influence on the net impact of oral calcium supplementation to all multiparous cows and accounted for 30% of the variation in net herd financial impact of oral calcium administration. Other variables that explained at least 5% of the variation in financial impact included decreased risk of health events in lame cows, herd prevalence of lameness, and milk price. Whereas supplementation of all postpartum multiparous cows returned a positive net herd impact approximately 80% of the time, if a herd was willing to devote time to mature-equivalent milk yield calculations and locomotion scoring, supplementation of this subpopulation of postpartum cows with oral calcium was estimated to have a positive economic impact in all iterations. Depending on the supplementation strategy chosen and baseline milk yield and immediate postpartum lameness prevalence in a herd, a herd with 1,000 calvings per year can expect to see an average net impact ranging from approximately $3,000 to $8,000 after postpartum supplementation of oral calcium in multiparous animals.