In Hong Kong, approximately one million people are affected by severe road traffic noise. It is crucial to estimate the vertical distribution of traffic noise levels at different levels in high-rise buildings during the planning and design stages for new residential buildings. The Calculation of Road Traffic Noise (CRTN) has been adopted in Hong Kong to estimate traffic noise from the road. However, there have been criticisms of the CRTN model’s accuracy and suitability for predicting road traffic noise in Hong Kong. This study examines and evaluates the accuracy of the CRTN method in predicting the vertical distribution of traffic noise level LA10 at different floor levels of a 20-storey residential building in Hong Kong. Also, measurements have been conducted of the traffic noise levels at each floor level of the building. Both the predicted and measured LA10 show a similar trend: the higher the floor level, the lower the traffic noise levels. However, the predicted LA10 at the building façade has a tendency of overestimation, especially at the higher floor levels, with a mean difference of +2.0 dBA between the predicted and measured results. A correlation coefficient (R2) of 0.9331 between the predicted and the measured LA10 indicates that the predicted levels correlate closely with the measured levels. The CRTN is therefore a useful tool in predicting traffic noise levels at different floor levels during the building planning stage. Practical application: This study provides an evaluation of the accuracy of the CRTN method in predicting the vertical distribution of traffic noise level at different floor levels of a residential building. It suggests that the CRTN is a useful tool in predicting traffic noise levels at different floor levels during the building planning stage.