Fat quantification by MRI plays an important role in assessing hepatic steatosis and bone marrow changes. We propose a new method for fat quantification in which multiband pulses are used to separately but simultaneously excite fat and water. CAIPIRINHA encoding allows overlapping images of the two species to be separated. Fat fraction maps can be calculated from fat and water images with appropriate consideration of relaxation times. The proposed method is validated on phantoms with different fat concentrations, where it yields similar fat fraction values to the Dixon approach and single-voxel spectroscopy.