As seaweed farming gains prominence in future blue economies, scientifically robust environmental evaluations are vital. Harmonizing life cycle assessment (LCA) studies provides nuanced insights, allowing generalizations and potentially more accurate results than individual studies. This study recalculates life cycle inventory (LCI) data to offer a comprehensive perspective on sugar kelp Saccharina latissima. The findings affirm and validate previous studies, emphasizing critical hotspots such as fuel use for boats at sea, impacts from the use of plastic ropes, buoys and metal components at sea, and electrical energy use in the hatchery. The overall environmental impacts of seaweed farming remain relatively low compared to other seafood and biomass sources. The study also highlights the importance of how fuel use is modelled for the outcome. While harmonization enhances certainty and facilitates robust comparisons, challenges arise from the lack of standardized methods for data collection and reporting, along with data gaps between studies. Addressing these limitations calls for standardized protocols and improved data sharing practices in the field.