As the effects of global warming have become more evident, ambitious short-term greenhouse gas emission reduction targets have been set in recent years. Many cities worldwide have adopted an active approach to climate change mitigation, but policy makers are not always knowledgeable of the true effects of their planned mitigation action. The purpose of this paper is to evaluate the effectiveness of different mitigation strategies in achieving low-carbon urban communities. The assessment is conducted via means of consumption based hybrid life-cycle assessment, which allows the reduction potential to be analyzed from the perspective of an individual resident of the urban community. The assessed actions represent strategies that are both adopted by the case cities and possible to implement with current best practices in Finland. The four assessed actions comprise: (1) dense urban structure with less private driving; (2) the use of energy production based on renewable sources; (3) new low-energy residential construction; and (4) improving the energy efficiency of existing buildings. The findings show that the effectiveness depends greatly on the type of city, although in absolute terms the most significant reduction potential lies with lowering the fossil fuel dependence of the local energy production.