<p>We consider a fleet of elementary robots that can be connected in different ways to transport loads of different types. For instance, a single robot can transport a small load and the association of two robots can either transport a large load or two small loads. The robot associations can be reconfigured between two trips. We seek to determine the minimum number of robots necessary to transport a set of loads in a given time interval. We formulate this fleet sizing problem with an integer linear program. We also derive analytical expressions for the minimum number of robots in the special case of unit capacities. Finally, we compare the minimum number of robots with or without reconfiguration. We show that the value of reconfigurability can be very high and diminishes with the fleet size. Reconfigurability is particularly useful when the demand for small loads has to be met at a different time interval from the demand for large loads. Finally, numerical experiments show that we can obtain the optimal solution in a short computation time when the number of load types and configurations is reasonable, which corresponds to many warehouse configurations.</p>