Measurement of hadronic cross section at KLOE/KLOE-2

The measurement of the $\sigma (e^{+}{e}^{-}\to {\pi }^{+}{\pi }^{-})$ cross section allows to determine the pion form factor $\mathrm{\mid }{F}_{\pi }{\mathrm{\mid }}^2$ and the two pion contribution to the muon anomaly $a_{\mu }$. Such a measurement has been performed with the KLOE detector at $DA\mathrm{\Phi }NE$, the Frascati $\varphi$-factory.The preliminary results on the combination of the last analysis (KLOE12) with two previous published (KLOE08, KLOE10) will be presented in the following.