The Government and the Joint Monitoring Programme for Water and Sanitation (JMP) sanitation monitoring approaches often produce conflicting sanitation estimates reflecting an inconsistent view of sanitation performance. One of the possible reasons for conflicting estimates is the differences in definitions of ‘improved sanitation access’. This paper presents an assessment of definitions used in Sub-Saharan Africa and an analysis of the impact of the two monitoring approaches on sanitation estimates. Results showed that 40.0% of the 35 countries analysed used stricter definitions than the JMP definition, while 22.2 and 37.1% used more lenient definitions and JMP-like definitions respectively. Independent samples t-test results showed significant differences (p≤ 0.05) between the Government and JMP sanitation estimates. The Bland–Altman analysis showed that on average the Government approach measured more than the JMP approach and that the highest frequencies of negative differences were obtained from countries using JMP-like definitions. The study concludes that the overestimation of Government sanitation estimates could not have been due to use of lenient definitions, but other factors such as the quality and quantity of data sources and methods of data analysis could have played a crucial role. Harmonization of definitions and methods in all survey instruments is, however, crucial to ensuring consistency in the post-2015 sanitation monitoring.