Consumer’s calorie estimation plays an important role in food consumption choices. However, calorie estimation is often objective and biased based on many factors. One of the most important factors is saltiness. Hardly any studies exist to show the influence of saltiness on food consumption. While the association of saltiness and unhealthiness is obvious in daily life routines, it is very likely to have an effect on calorie estimation. The purpose of this study is to examine the effect of saltiness on calorie estimation. We conducted four studies to examine our hypothesis. We adopted a laboratorial food taste task in study 1. Participants were randomly assigned into two groups (saltiness: strong vs. weak). They were asked to estimate the calorie content of the peanuts after eating them. The stimuli in two groups were the same except for the salt content. In order to examine the robustness of the effect among different age-groups and people from different regions, we enlarged our sampling to include young adults and elders, northerners and southerners in study 2. Participants were randomly assigned into two groups (saltiness: strong vs. weak) then they were shown a description of the type of food. Additionally, the mediating role of perceived healthiness is tested in study 2. We manipulated the healthy perception of salt in study 3 to test the mechanism indirectly. In the manipulated group, the participants were shown a report implying that salt could benefit us, while in the control group, the report showed that a smile was healthy. In study 4, we examined further the moderating role of food category as well as the mediating role of perceived healthiness in the effect of saltiness on calorie estimation with a 2 (saltiness: strong vs. weak) × 2 (food category: healthy vs. unhealthy) between subject design. Participants were randomly divided into 4 groups and showed a description of food (e.g., chips mixed with salt). In all studies, participants needed to estimate the calorie content of the food described. As predicted, we found that consumer’s estimation in calorie would significantly increase when food was saltier. The effect is robust among different age groups as well as participants from Southern China and Northern China. Nevertheless, when salt was primed to be a healthy element to our body, the increase of calorie estimation in saltier food no longer existed. Moreover, food categories played a moderating role. Consumers were more likely to overestimate the number of calories in saltier healthy food than in unhealthy ones. Furthermore, the results showed that participants perceived healthiness mediate the effect of saltiness in calorie estimation. As perceived healthiness increased, consumers’ estimation of calorie increased as well. The mediating effect existed only in healthy foods. These results enrich literature regarding calorie estimation. First, this study explored the field of taste in which it is the most related factor in food consumption. Secondly, it added the evidence that calorie estimation is irrational and easily biased due to salt itself contains zero calories. Third, we examined the perceived healthiness as a mechanism to the effect. Moreover, this study has shown some insight for companies. By making food products less salty, sales may increase not only because it may seem healthier to consumers but it may also cause consumers to underestimate the amount calorie intake.