Extreme ultraviolet (EUV) lithography flare calculation and compensation is disclosed herein. A method of calculating flare for a mask for use in EUV lithography includes decomposing the flare power spectrum density (PSD) into a low frequency component and a high frequency component. Further, the method includes receiving a plurality of layouts in a flare map generator. Each of the plurality of layouts corresponds to a chip pattern location on the mask. Moreover, the method includes generating, using the flare map generator, a low frequency flare map for the mask from the low frequency component by using fast Fourier transform (FFT).