This review updates previous estimates of contraceptive failure rates for all methods available in the United States, distinguishing between typical use (inconsistent or incorrect use) and perfect use (correct and consistent use). The difference between these rates reflects the impact of imperfect use on effectiveness. The study uses data from the 1995 and 2002 National Surveys of Family Growth (NSFG) and other clinical trials to estimate failure rates. For typical use, the probabilities of pregnancy are based on real-world usage, while perfect use estimates are derived from studies where methods are used as instructed. The study highlights that many methods have lower failure rates in perfect use than in typical use, but the gap varies by method. For example, the female condom has a 12.4% pregnancy rate during typical use and a 2.6% rate during perfect use. The male condom has a 12.4% typical use rate and a 2% perfect use rate. Fertility awareness-based methods have varying rates, with the Standard Days method at 4.8% and the symptothermal method at 0.4 per 100 women-years. The diaphragm has a 4.3-8.4% perfect use rate, while the sponge has a 19.4-20.5% perfect use rate. Intrauterine devices (IUCs) have very low failure rates, with ParaGard at 0.8% and Mirena at 0.2%. Sterilization has a 0.02% failure rate in perfect use. The study also notes that contraceptive continuation rates vary by method, with some methods having higher continuation rates than others. The Lactational Amenorrhea Method (LAM) is highly effective, with over 98% protection in the first six months postpartum under ideal conditions. The study concludes that understanding both typical and perfect use rates is essential for making informed contraceptive choices.This review updates previous estimates of contraceptive failure rates for all methods available in the United States, distinguishing between typical use (inconsistent or incorrect use) and perfect use (correct and consistent use). The difference between these rates reflects the impact of imperfect use on effectiveness. The study uses data from the 1995 and 2002 National Surveys of Family Growth (NSFG) and other clinical trials to estimate failure rates. For typical use, the probabilities of pregnancy are based on real-world usage, while perfect use estimates are derived from studies where methods are used as instructed. The study highlights that many methods have lower failure rates in perfect use than in typical use, but the gap varies by method. For example, the female condom has a 12.4% pregnancy rate during typical use and a 2.6% rate during perfect use. The male condom has a 12.4% typical use rate and a 2% perfect use rate. Fertility awareness-based methods have varying rates, with the Standard Days method at 4.8% and the symptothermal method at 0.4 per 100 women-years. The diaphragm has a 4.3-8.4% perfect use rate, while the sponge has a 19.4-20.5% perfect use rate. Intrauterine devices (IUCs) have very low failure rates, with ParaGard at 0.8% and Mirena at 0.2%. Sterilization has a 0.02% failure rate in perfect use. The study also notes that contraceptive continuation rates vary by method, with some methods having higher continuation rates than others. The Lactational Amenorrhea Method (LAM) is highly effective, with over 98% protection in the first six months postpartum under ideal conditions. The study concludes that understanding both typical and perfect use rates is essential for making informed contraceptive choices.