In 2003 the IMAG Drift Calculator was developed to compute downwind spray deposits onto surface water. Recently, it was renewed, improved and expanded resulting in the current WUR Drift Calculator. This calculator is a tool to quantify spray drift to surface waters and non-target areas near a sprayed field or orchard. The calculator uses statistically obtained regression curves to calculate spray deposition next to the sprayed field. These spray drift curves are derived from experimental drift data for field crops, fruit orchards and avenue tree nurseries. The calculator is intended for computation of spray drift deposits onto the surface water next to a field crop, fruit orchard or avenue tree nursery. It can also be used to compute spray drift deposits onto off-field terrestrial non-target zones, to evaluate exposure of non-target plants and arthropods (NTP, NTA) to pesticides. Drift mitigation measures such as additional buffer zones and the use of drift reducing application techniques, represented by their DRT classes (DRT50 up to DRT99), can be selected as well. For field crops, a distinction is made between applications on bare soil (including low-height emerging crops) and applications on higher or full-grown crops. For fruit orchards, dormant trees and trees in full leaf are distinguished. With avenue tree nurseries, a distinction between spindle trees, transplanted trees and high avenue trees is available.