This study explores the ‘15-minute city’ concept in Hamilton, New Zealand, focusing on challenges related to car dependency and urban sprawl. Triggered by the greater emphasis on sustainable urban environments following the global pandemic, the research employs a mobility-based approach to assess the model's applicability across various urban districts. Geographic Information System (GIS) mapping is used to identify ‘liveable areas’ in business, residential, and industrial districts where essential services are accessible within three different thresholds of 5, 10, and 15 min walking distance. This tiered approach offers a detailed view of urban accessibility, highlighting the practicality and varying implementation levels of the 15-minute city concept across diverse urban areas. Geolocated mobile phone data from 88,660 residents is analysed with a focus on ‘inflow’ and ‘outflow’ travel distances at both city and district levels. While the results reveal the practical challenges of implementing the ‘15-minute city’ paradigm, they also show partial alignment of Hamilton's urban fabric with the paradigm, offering scope for adjustments to better suit the city's specific characteristics and residents' behaviours. The study highlights opportunities for enhancing the diversity and accessibility of amenities and improving public transportation and alternative transport options, all key factors for sustainable urban development. This adaptable methodology serves as a valuable reference for other cities in developing strategies for sustainable living. The study concludes that while Hamilton shows potential for transformation, a nuanced and locally focused approach is crucial. These insights contribute to the current new urbanist literature by providing a comprehensive city-district perspective, extending the discourse to include distances beyond the ‘15-minute city’ and highlighting areas where further urban planning or intervention is necessary.