Due to advances in experimental techniques operating at the nanoscale, it is possible to compute properties from density fluctuations by studying 'snapshots' of particle configurations. Thermodynamics on a small scale is different from thermodynamics in bulk systems. We show how the molar enthalpy h and the inverse thermodynamic correction factor Gamma(-1) depend on system size and how these properties can be computed from fluctuations at the nanoscale. We find a 1/L finite size effect for all thermodynamic quantities for a small system in contact with a reservoir, where L is the length of the system in a single dimension. (C) 2011 Elsevier B.V. All rights reserved.