A time-dependent zero-dimensional code has been developed to assess the pulse length and auxiliary heating requirements of Compact Ignition Tokamak (CIT) designs. By taking a global approach to the calculation, parametric studies can be easily performed. The accuracy of the procedure is tested by comparison with the Tokamak Simulation Code, which uses theory-based thermal diffusivities, A series of runs is carried out at various levels of energy confinement for each of three possible CIT configurations. It is found that for cases of interest ignition or an energy multiplication factor Q ≳ 7 can be attained within the first half of the planned 5-s flattop with 10 to 40 MW of auxiliary heating. These results are supported by analytic calculations.