Calving date affects cow winter feed cost, calf survival, and calf weight on a given market date. To optimize pounds of calf sold relative to winter feed cost producers need to quantify the effect of calving date on preweaning calf gain and cow winter feed costs. A study was conducted using on-farm records of calving date and weaning weight for 1159 calves over 18 farm/years. Birth weight was estimated to average 83 lb for steers and 81 lbs for heifers based on a 6-year average for one beef herd of similarly bred animals. Weight per day of age (WDA, lbs) was calculated as weaning weight minus calf gender estimated birth weight, divided by age in days at weaning. The data was analyzed by regression using farm and calf gender as discrete variables. Pre-weaning WDA was 1.85 on January 1, increasing 0.00382 lbs per day as calving was delayed from January 1 to April 14; steers gained 0.21 lbs/day more than heifers; and WDA differed by farm (from -0.37 to + 0.72 lbs/day) due to animal genetics and animal and pasture management (r²=0.38, Regression SD = 0.29). The value of calf gain was compared across calving dates for high versus low market income and high versus low feed costs experienced in West Virginia over the last ten years. Under high feed costs and low markets calves born on February 28 and March 31 returned $16 and $38/head less than those born on January 31. Under low feed costs and high market calves born on February 28 and March 31 returned $36 and $84/head less than those born on January 3. The higher return for early born calves may be a small margin to cover for differences in conception and mortality rate that can be due to calving date.