Here we demonstrate that significant variability is present in GUVs composed of a ternary DSPC:POPC:CHOL mixture. It is shown that GUVs formed via electroformation have considerably less compositional variability than those formed via gentle hydration. This is true regardless of whether the relative change in concentration between two labeled species is calculated or if the variability in absolute concentration is determined via external calibration curves. Although the mechanism behind the lower variability seen in electroformed GUVs is unclear, it is clear that ternary mixtures are far more variable than pure mixtures and that preferential interactions between certain lipids are present in the films used to form ternary GUVs.