Suppose that η is a Schramm-Loewner evolution (SLEκ) in a smoothly bounded simply connected domain D⊂C and that ϕ is a conformal map from D to a connected component of D∖η([0,t]) for some t>0. The multifractal spectrum of η is the function (−1,1)→[0,∞) which, for each s∈(−1,1), gives the Hausdorff dimension of the set of points x∈∂D such that ∣ϕ′((1−ϵ)x)∣=ϵ−s+o(1) as ϵ→0. We rigorously compute the a.s. multifractal spectrum of SLE, confirming a prediction due to Duplantier. As corollaries, we confirm a conjecture made by Beliaev and Smirnov for the a.s. bulk integral means spectrum of SLE and we obtain a new derivation of the a.s. Hausdorff dimension of the SLE curve for κ≤4. Our results also hold for the SLEκ(ρ) processes with general vectors of weight ρ