The ignition delay times of n-C7H16, i-C8H18, and a blend of them at different fuel, O2 and N2 concentrations were computed using a detailed chemical kinetic mechanism generated by KUCRS. For each fuel, the dependences of ignition delay time on fuel, O2 and third body concentrations and on the heat capacity of a mixture were distilled to establish a power law equation for ignition delay time. For n-C7H16, ignition delay time τhigh without low-temperature oxidation at a high initial temperature between 1000 K and 1200 K was expressed using the scaling exponents for fuel, O2 and third body concentrations and heat capacity of 0.54, 0.29, 0.08, and - 0.38, respectively. Low-temperature oxidation induction time τ1 at a low initial temperature between 600 K and 700 K was expressed using the scaling exponents for fuel, O2 and third body concentrations and heat capacity of 0.03, 0.18, 0.04, and - 0.17, respectively. Total ignition delay time with low-temperature oxidation was expressed as τlow = B·(τhigh - τ1) + τ1 using extrapolated τhigh and τ1. B was expressed as an exponential function dependent on fuel, O2 and third body concentrations and the heat capacity of a mixture, or set for 1 when initial temperature was higher than a high-temperature limit for low-temperature oxidation, which was also dependent on fuel, O2 and third body concentrations and the heat capacity of a mixture. The equations for τhigh and τlow successfully estimated the ignition delay time computed using the detailed chemical kinetic mechanism.