Children are likely to assume very awkward seated postures when using a desktop computer at workstations with limited adjustability. This also includes the workstations that are not built for them such as adult visual display terminal (VDT) workstations. This paper proposes simple step-by-step procedures for estimating necessary adjustments so that children can sit and maintain an appropriate seated posture at VDT workstations with limited adjustability (i.e., fixed keyboard and monitor heights). From the anthropometric and VDT workstation data, the procedures compute the recommended VDT workstation settings for a concerned child, compare them with the actual workstation adjustment ranges, determine the appropriate settings, and suggest necessary accessories. The posture adjustment procedures are tested on four Thai children seated at two different types of adult VDT workstation. A rapid upper limb assessment (RULA) technique is used to evaluate the children's seated postures both before and after the posture adjustment. Applying the procedures, children need their own VDT workstation that should be fully adjustable. In using an adult workstation, adjustment accessories and the correct settings are required.