To evaluate the status of biodiversity and to determine how current conservation efforts can be improved, biodiversity monitoring is crucial. An important aspect of data quality lies in its spatial resolution. It is unclear how finer scale land cover and land value information might further benefit biodiversity conservation. This paper aimed to assess the impacts of scale by modelling the conservation of endangered European wetland species and their corresponding habitats. Fine-scale datasets were derived by integrating existing geographical, biophysical and economic data. A habitat allocation model, based on principles from systematic conservation planning and economic theory, was developed to estimate area requirements and opportunity costs of habitat protection in Europe. Coarse-scale and fine-scale simulations were compared by inputting both resolutions into the model. Habitat locations were restricted either only by historical species occurrence data at UTM 50 resolution or additionally by explicit wetland data at 1-km2 resolution. Coarse country-average land rents were contrasted with spatially detailed land rent estimates at a 5ʹ resolution. Costs of habitat protection and area requirements for reserves may be severely underestimated when conservation planning relies only on coarse-scale data, which may result in notable shortcomings in conservation target achievement. Improvements in conservation benefits far outweigh the additional costs of acquiring fine-scale data.