Unintended pregnancy is reportedly higher in active duty women; therefore, we sought to estimate the potential impact of the levonorgestrel-containing intrauterine system (LNG-IUS) could have on unintended pregnancy in active duty women. A decision tree model with sensitivity analysis was used to estimate the number of unintentional pregnancies in active duty women which could be prevented. A secondary cost analysis was performed to analyze the direct cost savings to the U.S. Government. The total number of Armed Services members is estimated to be over 1.3 million, with an estimated 208,146 being women. Assuming an age-standardized unintended pregnancy rate of 78 per 1,000 women, 16,235 unintended pregnancies occur each year. Using a combined LNG-IUS failure and expulsion rate of 2.2%, a decrease of 794, 1588, and 3970 unintended pregnancies was estimated to occur with 5%, 10% and 25% usage, respectively. Annual cost savings from LNG-IUS use range from $3,387,107 to $47,352,295 with 5% to 25% intrauterine device usage. One-way sensitivity analysis demonstrated LNG-IUS to be cost-effective when the cost associated with pregnancy and delivery exceeded $11,000. Use of LNG-IUS could result in significant reductions in unintended pregnancy among active duty women, resulting in substantial cost savings to the government health care system.