Calculations of the relic density within the MSSM rely on information about the mass both of the LSP and of other particles which play a key role in the dominant mechanisms of annihilation. Direct searches at the LHC have not yet detected any SUSY particles, however in the upcoming 14 TeV run ATLAS and CMS will close in on sub-TeV electroweakinos and third generation fermions. The extremely high precision measurements (< 1%) expected to be achievable at the linear collider would further provide us with much improved sensitivity to many of the relevant MSSM particles, including those appearing only via loop effects. In the talk we analyze several phenomenologically motivated scenarios, derive projected errors on the relic density prediction from combined measurements at LHC and different LC options and discuss the implications for dark matter models.