Microdrilling based on laser ablation has been widely applied for manufacturing micro-/nanofeatures on different materials as a noncontact thermal removal approach. It has the advantages of high aspect ratio manufacturing capability and reduced surface damage. However, laser ablation is a complicated process that is challenging to model. In this paper, a standardized modeling procedure was demonstrated to predict the area and depth of laser ablation based on experimental study and simulation validation. A case study was conducted where microdrilling of high-density polyethylene (HDPE) was investigated using a 1064 nm nanosecond pulsed laser. Blind microholes were fabricated on the HDPE samples by ablating under different laser powers and numbers of pulses. Gain factors were defined and determined by the experimental data. A quantitative area-depth approximation model was formulated based on the gain factors. A comparison of the measured and the simulated results of microholes presented average 96.5% accuracy for the area and 85.7% for the depth. This research provided a simple but effective approach to predict dimensions of microholes on various substrates using laser ablation under different laser powers and the numbers of pulses, which could pave the way for development and modeling of laser ablation on polymers.