Prostitution regimes in the EU-28 include prohibition, regulation and abolition; we tackle this typology from the perspective of both free sex work and forced labour, in order to gauge the magnitude of the European sex market as of 2010. We document the behaviour of customers on the demand-side for prostitution. Next, we address the supply-side, using HIV prevalence among sex workers to achieve a first series of two estimates. We design a second series of two estimates from miscellaneous sources (NGOS and the police). We investigate forced sexual labour trafficking, providing an additional series of estimates from the ILO and from Eurostat and UNODC. We check the magnitude of prostitution as regards employment figures and ranking with respect to the distribution of population in the EU countries. Thanks to an ordered probit, we test all five estimates; eventually, we come up with one best estimate (from HIV prevalence) that is also the lowest one.