As described in the work of Mietke et al. (1) the deformation (defined as 1 - circularity [see (2)]) of a purely elastic, spherical object deformed in a real-time deformability cytometry (RT-DC) experiment can be mapped to its apparent Youngs Modulus. This note is supposed to help a fast and correct mapping of RT-DC results - namely, deformation and size - to values of the apparent Youngs Modulus E.