OBJECTIVES To design a computerised system of calculating resuscitation requirements and to test this system to ensure that it gives accurate and fast results, so that it could potentially be used in the resuscitation of patients in a accident and emergency (A&E) department. METHODS Using internet based technology we have developed a program that runs inside most web browsers and can be used to calculate several parameters (including endotracheal tube dimensions and drug doses). The only value that is required is the age of the patient. The weight is calculated and can be adjusted if known. The resuscitation requirement calculations are made from the weight. The program was then tested on staff members in the department to calculate theoretical resuscitation requirements for paediatric and adult patients. Accuracy and speed of the computerised calculator was compared with the conventional paper based calculation methods. RESULTS Subjects performed better using the computerised calculator. On average they made significantly fewer errors (21.4% more accurate than using conventional methods) and were three times faster. CONCLUSION The computerised calculator has proved, in a controlled setting, to be a more accurate and faster way of calculating resuscitation requirements than conventional methods.