In the present article, we report new density data for monoethylene glycol dimethyl ether (MEGDME) and for diethylene glycol dimethyl ether (DEGDME) at several temperatures between 293.15 K and 353.15 K and up to 60 MPa. A vibrating tube densimeter with an uncertainty of +/-1 x 10(-4) g.cm(-3) was used for density measurements. The experimental density data (182 points) were fitted to the Tait-like equation with standard deviations of less than 2 x 10(-4) g.cm(-3). Using these correlations, the isobaric thermal expansivity, alpha(p), the isothermal compressibility, kappa(T), and the internal pressure, pi, have been obtained for MEGDME and DEGDME. To analyze the trend of these. properties with the chain length of polyalkylene glycol dimethyl ethers, their pressure and temperature dependences have been compared with the results found before for triethylene glycol dimethyl ether and for tetraethylene glycol dimethyl ether. The ability of different cubic equations of state to predict the volumetric properties of MEGDME and DEGDME was tested, obtaining the best results with the Peng-Robinson equation of state.