Larson E, et al. - Emergency contraception (EC) use estimates using five approaches were compared. Researchers retrieved data from Performance Monitoring and Accountability 2020 surveys from 10 countries, representative sample surveys of women aged 15 to 49 years. EC use was determined utilizing the five definitions and absolute differences were calculated between a reference definition (percentage of women currently using EC as the most effective method) and each of the subsequent four, including the most inclusive (percentage of women having used EC in the past year). Great variation was observed in estimated use by definition across the 17 geographies, and EC use employing the most inclusive definition is statistically significantly higher than the reference estimate. Unmarried sexually active women exhibited most pronounced impact of using various definitions. The magnitude of EC use is likely underestimated by the conventional definition of EC use, which has unique programmatic implications.