Abstract A barrier to controlling the amount of food consumed may be the difficulty consumers have in accurately estimating portion sizes. Although portion size measurement aids (PSMAs) can improve estimation accuracy, their bulk and/or cost tends to make them impractical for regular use. The purpose of this study was to investigate the effect on portion size estimation accuracy of two practical PSMAs: a 2-D PSMA (life size picture of tennis and golf balls) and 3-D PSMAs (tennis and golf balls). Young adults were randomly assigned to one of two groups and estimated the portion sizes of 36 foods divided into three equal sets. PSMAs were not used to estimate portion sizes in Food Set 1. Study group 1 (n = 57) used the 2-D PSMA and study group 2 (n = 56) used the 3-D PSMAs to estimate the portion sizes in Food Set 2. Neither group used PSMAs to estimate portion sizes in Food Set 3. Repeated measuresanovaindicated that both groups significantly improved estimation accuracy between Food Sets 1 and 2 and between Foods Sets 1 and 3. Thus, even short-term exposure to practical PSMAs may improve estimation accuracy and these improvements persist when the PSMA is no longer available. However, the accuracy rate for Food Set 2 was only about 60% indicating that a great deal of estimation error remains.