A retrospective review of data from a lactation program's productivity reports at a large tertiary care teaching hospital (4200 births per year) measured actual hours worked by international board certified lactation consultants (IBCLCs) over a 2-year period, allocated the hours to their respective activities, and developed ratios for optimal IBCLC staffing for each component of service delivered. Optimal IBCLC staffing was calculated as follows: mother/baby inpatient requires 1 full-time equivalent (FTE) per 783 breastfeeding couplets; neonatal intensive care unit (NICU) inpatient requires 1 FTE per 235 infant admits; mother/baby outpatient requires 1 FTE per 1292 breastfeeding couplets discharged; NICU outpatient requires 1 FTE per 818 breastfeeding infants discharged; telephone follow-up requires 1 FTE per 3915 breastfeeding couplets or infants discharged; education requires 0.1 FTE per 1000 deliveries; program development/administration requires 0.1 FTE per 1000 deliveries; and research requires 0.1 to 0.2 FTE total. Using the formulas provided, IBCLC staffing can be calculated for desired services based on patient numbers.