The Webb-Pearman-Leuning (WPL) formula is used to minimize the overestimate CO2 flux by open-path gas analyzer and eddy covariance methods. However, its effectiveness for tropical coastal waters with high air water vapor content requires investigation. This paper assesses the WPL correction on CO2 flux measurement over the tropical coastal water using three calculation methods: standard (including WPL and other correction methods), raw, and WPL. The results showed that the standard method yielded CO2 flux of –0.10 µmol m–2 s–1, which is 60% lower than the raw. The WPL-CO2 flux (–0.07 µmol m–2 s–1) is also lower than the raw (–0.25 µmol m–2 s–1) by 0.17 µmol m–2 s–1. The WPL formula serves its purpose in minimizing the CO2 flux overestimation but uses caution with the formula as it can change positive-negative flux signs, especially with temperature and water vapor corrections.