The isotropic magnetic susceptibility, chi(iso), for F-2 has been measured experimentally for the first time and found to be (-9.627 +/- 0.062) x 10(-6)(cgs). The value was measured on a paramagnetic gas analyzer (PGA) configured to be compatible with the aggressive F-2. The PGA was Shown to respond linearly with chi(iso) and was calibrated using the response from several pure gases and their literature chi(iso) values. The major source of error in the analysis is the inaccuracy of the literature chi(iso) values. The experimental result for F-2 was compared to ab initio calculations using both Hartree-Fock (HF) theory and gradient-corrected density functional theory (DFT) theory with a variety of basis sets. DFT calculations were found to converge to a value much closer to the experimental value compared to HF calculations, underlining the importance of the many-electron correlation effect in F-2.