A method of determining particle size distribution from multi-angle dynamic light scattering data, comprising: obtaining a series of measured correlation functions g(θi) at scattering angles θi; and solving an equation comprising [ g ⁡ ( θ 1 ) … g ⁡ ( θ n ) ] = [ α 1 ⁢ K ⁡ ( θ 1 ) … α n ⁢ K ⁡ ( θ n ) ] ⁢ x , wherein: K(θi) is the instrument scattering matrix computed for angle i, x is the particle size distribution, and αi is the scaling coefficient for angle i. The method comprises using the steps: a) providing initial estimates for scaling factors α2 to αn, and defining α1=1; b) iterating scaling factors α2 to αn using a non-linear solver; c) solving for x using a linear solver; d) calculate residual; e) repeat steps b) to d) while the residual is greater than a predefined exit tolerance.