The importance of the rise angle of bubbles on the influence of local bubble-size distribution in fluidized beds was studied. A new method is proposed for transforming chord-length distribution to a local bubble-size distribution, including the effect of the velocity vector direction on the transformation. Monte-Carlo simulation was used to generate bubbles synthetically with several rise angels, based on the fact that the velocity vector direction distribution of bubbles was a Bingham distribution. The transformation of chord-length data obtained by an imaginary probe, using the Parzen window as an estimation of the probability density function, gives a good estimation of the local bubble-size distribution for different rise angles and the new approach offered here, knowing that the direction of the velocity vector direction for any orientation of the bubbles in the fluidized bed gives a superior agreement than the approach where the local bubble-size distribution is estimated from bubbles with vertical rises.