Experiments measuring the extension of moderately confined double-stranded DNA within nanochannels have consistently shown a stronger scaling relationship between extension length and nanochannel confining dimensions than predicted by theory. Contrary to past findings, in this article the DNA extension length (R) was found to scale with D eff in close agreement with the theoretically predicted relationship (R ∼ D eff −2/3) and simulation results, with best-fit exponent values ranging from −0.67 to −0.70 across three unique devices. In addition, the power law fits of the experimental data exhibited close agreement with an exact model in the extended de Gennes regime, with fit prefactors within 10% of the expected value. A comparison of device dimensions against those used in previous experiments is presented to reconcile current findings with past results, suggesting that modest aspect ratios in rectilinear channels do not appreciably affect scaling, whereas the smallest dimension of a nanochannel can strongly impact extension. The results are also in quantitative agreement with recent unified theories describing the scaling of DNA extension across various conformational regimes.