This study aimed to examine the relationship between an object's physical size and judgements of its value. Two preregistered experiments were performed to explore a size-value compatibility effect. Two images of Japanese-yen coins with different values but similar actual sizes (10-yen and 100-yen) were manipulated for size and presented side-by-side on a computer screen. Participants judged which coin was larger or smaller based on the images. Results revealed that size judgements were slower and less accurate when the lower-value coin was presented as larger than the higher-value coin, compared to when the lower-value coin was presented as smaller. This effect was observed even after participants had been allowed to examine the physical coins prior to the experiment to judge their actual size. This finding suggests that participants perceived the coins' values based on their sizes, indicating it may be difficult for many people to stop thinking 'better is bigger'.