New ignition delay time (IDT) data for stoichiometric natural gas (NG) blends composed of C1–C5 n-alkanes with methane as the major component were recorded using a high pressure shock tube (HPST) at reflected shock pressures (p5) and temperatures (T5) in the range 20–30 bar and 1000–1500 K, respectively. The good agreement of the new IDT experimental data with literature data shows the reliability of the new data at the conditions investigated. Comparisons of simulations using the NUI Galway mechanism (nuigmech1.0) show very good agreement with the new experimental results and with the existing data available in the literature. Empirical IDT correlation equations have been developed through multiple linear regression analyses for these C1–C5 n-alkane/air mixtures using constant volume IDT simulations in the pressure range pC = 10–50 bar, at temperatures TC = 950–2000 K, and in the equivalence ratio (φ) range 0.3–3.0. Moreover, a global correlation equation is developed using nuigmech1.0 to predict the IDTs for these NG mixtures and other relevant data available in the literature. The correlation expression utilized in this study employs a traditional Arrhenius rate form including dependencies on the individual fuel fraction, TC, φ, and pC.