Spray coverage of leaves requires ideal estimate of total leaf area. In air carrier sprayer, spray liquid is carried to the target by air. The volume of air required is equal to the volume of the tree for effective coverage. To find out the air volume and velocity of blower and discharge rate of the spray nozzle, canopy size, canopy height, leaf area, foliage density and canopy volume of mango tree, the measurement of data on the mango trees were carried out. The overall canopy height above ground level, height to the point of maximum canopy diameter, height from ground to canopy skirt and canopy diameter parallel to the row was measured. The average leaf area per cubic metre canopy volume found out by measuring leaf area by leaf area meter. An ideal spraying would result in deposition of 20-25 droplets of 100 micron size /cm2 of leaf area. The droplet sizes greater than 250 micron are subjected to run off. So a good deposition would have 25 droplets of sizes less than 250 micron /cm2 of leaf area. Based on this, a method has developed to estimate spray volume requirement for effective pesticide application.