We report on the free volume of the Zr₄₄Ti₁₁Ni₁₀Cu₁₀Be₂₅ bulk metallic glass in terms of its enthalpy recovery and volumetric relaxation below the glass transition temperature, T_g. Glassy samples are isothermally annealed below T_g using differential scanning calorimetry and the resulting enthalpy recovery, ΔH_r, is measured upon re-heating into the supercooled liquid region. Volumetric changes below T_g are measured isothermally using Thermo-Mechanical Analysis. The total changes in the relative free volume, Δν_f/ν_m, between the initially glassy state and the equilibrium liquid are calculated from the volumetric relaxation. The measured values of ΔH_r and Δν_f/ν_m correlate well within the framework of free volume theory and a linear relationship is found between the two.