DA{phi}NE, the Frascati {phi}-factory, is an e{sup +}/e{sup -} collider with 2 interaction points (IPs). The center of mass energy is 1020 MeV and the design luminosity 4.2x10{sup 30} cm{sup -2} s{sup -1} in single bunch mode and 5x10{sup 32} cm{sup -2} s{sup -1} in multibunch mode. Between the possible electromagnetic reactions at the interaction point, single bremsstrahlung (SB) has been selected for the luminosity measurement. The SB high counting rate allows real-time monitoring, which is very useful during machine tune-up and moreover the narrow peak of the SB angular distribution makes the counting rate almost independent from the beam position at the IP. A description of the experimental set-up, calibration results and luminosity measurements is presented.