Abstract Traditionally, air requirements during an air drilling operation involve the utilization of the Angel's chart(s). The values from the mentioned chart(s) are generally 20-25% below the acutal field's requirements/needs. Recent studies in this area have provided more reliable results, however, the tedious calculations, the lack of proper charts, and the absence of the user-friendly programs have prevented their practical applications. The authors of this paper have developed a simplified model that takes into account both the material balance and momentum balance for the annulus. Air and cuttings have been treated independently in these balances. Multiphase momentum balance equation is adopted. This model will also accommodate the air lifting capacity in the annulus to be the dominant factor in deciding the air requirements.