  LUX-ZEPLIN (LZ) is a next generation dark matter direct detection experiment
that will operate 4850 feet underground at the Sanford Underground Research
Facility (SURF) in Lead, South Dakota, USA. Using a two-phase xenon detector
with an active mass of 7~tonnes, LZ will search primarily for low-energy
interactions with Weakly Interacting Massive Particles (WIMPs), which are
hypothesized to make up the dark matter in our galactic halo. In this paper,
the projected WIMP sensitivity of LZ is presented based on the latest
background estimates and simulations of the detector. For a 1000~live day run
using a 5.6~tonne fiducial mass, LZ is projected to exclude at 90\% confidence
level spin-independent WIMP-nucleon cross sections above $1.4 \times
10^{-48}$~cm$^{2}$ for a 40~$\mathrm{GeV}/c^{2}$ mass WIMP. Additionally, a
$5\sigma$ discovery potential is projected reaching cross sections below the
exclusion limits of recent experiments. For spin-dependent
WIMP-neutron(-proton) scattering, a sensitivity of $2.3 \times
10^{-43}$~cm$^{2}$ ($7.1 \times 10^{-42}$~cm$^{2}$) for a
40~$\mathrm{GeV}/c^{2}$ mass WIMP is expected. With underground installation
well underway, LZ is on track for commissioning at SURF in 2020.
