The amorphous phase state of suspended nanoparticles affects their atmospheric lifetimes and environmental impact. Influence of relative humidity and chemical composition on the glass-to-liquid transition is well-known. However, the influence of the particle size on the phase transition remains uncertain. Here we show experimental data that probe the amorphous phase transition of suspended sucrose particles as a function of particle size. The depression in glass-transition temperature follows the Gibbs-Thomson or Keesom-Laplace predicted proportionality of ΔT_g ∝ D^-1 for particles 100-700 nm in diameter, but the proportionality changes to ΔT_g ∝ D^-1/2 for smaller sizes. Literature data for glass-transition temperature depression in thin films and nanoconfined compounds show similar and strong deviations from the expected D^-1 behavior. While the observed proportionalities remain incompletely understood, the results here provide evidence that the deviation from ΔT_g ∝ D^-1 is not attributable to substrate effects.