Some people need to know the largest or smallest for anything. With pterosaurs, this is quite variable, as many individuals will vary in size as they grow. There are however, some species that are at the extremes of the size range.
The smallest pterosaur to be found so far is Nemicolopterus crypticus and it was found in the Jiufotang Formation rocks of Liaoning, China. It is from the Early Cretaceous Era. The specimen has a wingspan of 25cm (10 inches).
By far the largest pterosaur is Quietzalcoatlus northropi from the Javelin Formation in Texas, USA. This pterosaur is from the last part of the Late Cretaceous Era and had a wingspan of 12m (39 feet). The picture below will give an idea of how big this pterosaur is in relation to a Spitfire aircraft.
Azhdarcho longicollis is also a very big pterosaur which may have been equally as big as Quetzalcoatlus, but its remains are less complete and the only realistic estimate of size is for a wingspan of 10m.