This thesis evaluates the battery performance of two widely known game engines and compares the results to find the most battery friendly choice. Unity and Unreal Engine 4 are the two engines being compared; it aims to fill the need for research around mobile games battery performance. Smartphones battery life issues becomes more and more common with the powerful smartphones we use in today’s society. They are becoming faster every year, but the batteries stay the same. Power hungry games are not uncommon to find on the biggest game market that has surpassed the combined income of PC and Console games. Tests were performed on an Android system where multiple applications were tested while the battery consumption was measured. The applications are testing how different 2D or 3D components will impact the battery consumption compared to their baseline idling consumption. This thesis provides instructions on how the test applications were developed and which components were included. The findings show that the components had very little impact on the battery consumption for both Unity and Unreal Engine 4. Unity consumed between 1,1 – 1,4 % (36-42mAh) battery for all applications, Unreal Engine 4 consumed between 1,3 – 1,6% (39-48mAh) battery. This thesis conclusion is that Unreal Engine 4 game components require more battery power than the corresponding components of Unity. Therefore, Unity is according to the findings of this thesis a more battery friendly game engine for android games. These results mean that those who looks to create a smaller 2D or 3D game would get a more battery friendly application if they chose to use Unity. However, the results are limited because of how features like gyro, GPS and bigger applications were not included in the performed test cases.