The electroweak sector of the Standard Model can be tested via precision measurements of fundamental observables. The ATLAS collaboration has recently measured the effective leptonic weak mixing angle using data collected during Run-1 of the LHC at a centre-of-mass energy of 8 TeV.
The result is $sin^2$ $\theta^l_{eff}$ = 0.23140 $\pm$ 0.00036, yielding a precision similar to that of the recently published Tevatron legacy result and to the most precise individual observable measurements from lepton colliders. The W-boson mass was first measured at the LHC in the ATLAS Collaboration using LHC Run-1 data at a centre-of-mass energy of 7 TeV. The obtained result is the most precise individual measurement of the W-boson mass $m_W$ = 80370 $\pm$ 19 MeV. Prospects of these electroweak measurements at the HL-LHC are also discussed.