Consider the solution Z(t, x) of the one-dimensional stochastic heat equation, with a multiplicative spacetime white noise, and with the delta initial data Z(0, x) = δ(x). For any real p > 0, we obtained detailed estimates of the p-th moment of e t/12 Z(2t, 0), as t → ∞, and from these estimates establish the one-point upper-tail large deviation principle of the Kardar-Parisi-Zhang equation. The deviations have speed t and rate function Φ + (y) = 4 3 y 3/2 . Our result confirms the existing physics predictions [LDMS16a] and also [KMS16].