Objectives: Current dietary recall methods used in low-resource settings are prone to errors in portion size estimation. This study investigated the preference for, ease of use perceptions, and accuracy of visual variables in portion size estimation aids (PSEAs) for dietary recall in Malawi. Visual variables tested included food shapes compared with photos, number of portion size options, photo angle, and simultaneous compared with sequential portion size image presentation. Methods: Ninety-six women aged 18-45 y served themselves portions of 5 foods (groundnuts, bananas, nsima, bean relish, vegetable relish) and water, which were weighed before and after consumption. We administered a meal recall through the use of a digital or printed PSEA 30 min after eating and assessed participants' preferences for and ease of use perceptions of the PSEAs through a structured interview. Across participants and foods, we calculated the percentage of PSEA selections within 20% of the actual gram weight of food or water consumed. Results: Participant preference and ease-of-use perceptions favored photos, 45°photo angle, and simultaneous presentation. Three-and 5-portion sizes had similar preference and ease-of-use perceptions, but 3 portions were slightly more accurate than 5 (28% compared with 25% within 20% of actual gram weight). A 45°photo angle was more accurate than a 90°photo angle (35% compared with 25%), as was a simultaneous compared with sequential presentation of images (41% compared with 31%). Accuracy was similar for other visual variables. Differences in preference and ease-of-use perceptions between digital and printed PSEAs were inconclusive, but will be further tested in an upcoming validation study. Conclusions: The results indicate that PSEA visual variables can be optimized to improve participants' experiences during, and enhance accuracy of, dietary recall. The results of this formative evaluation and the planned validation study can inform the development of PSEAs for dietary intake data in low-resource settings. Funding Sources RTI International. Supporting Images/Graphs Reliability and Validity of Digital Images to Assess Plate Waste in a Restaurant Setting (E05-02