Increasing human pressures can limit ecosystems' ability to maintain natural functions and meet sustainable development needs. Therefore, environmental carrying capacity (ECC) evaluation, as a decision-making support tool, plays a key role in identifying limiting factors and formulating management policies. The present study aims to assess changes in environmental carrying capacity in District 6 of Tehran City from 2019 to 2025. For this purpose, Shannon entropy weighting was applied to 19 indicators selected across three components: pressure, state, and response, within the pressure-state-response (PSR) framework. In addition, the Mann-Kendall and Pettitt’s tests were used to evaluate the trend and the Monte Carlo method was used to assess the uncertainty in ECC values from 2019 to 2025 in RStudio. Data import, preprocessing, and visualization were conducted using the readxl, dplyr, tidyr, ggplot2, tibble, and patchwork packages. The results revealed that the ECC value decreased from 0.72 in 2019 to 0.35 in 2025, representing a 51% reduction in environmental carrying capacity. Furthermore, the analysis demonstrated that the pressure component was the primary driver of variations in the ECC index, indicating a greater influence than the state and response components. Therefore, prioritizing the reduction of pressures at their source, strengthening preventative measures, implementing continuous monitoring of state indicators, and periodically assessing the effectiveness of management policies should be emphasized in environmental planning.