Infants possess basic capabilities to assess various quantitative properties such as number, size, and time. Preverbal discriminations are approximate, however, and similarly limited by ratio across these dimensions. Here, we present the first evidence that redundant quantitative unisensory information—namely, simultaneous visual cues to both number and size—accelerates six-month-olds’ quantitative competence. Using a habituation-dishabituation paradigm, results demonstrate that, when provided with synchronous visual cues to different quantitative properties, infants make more precise discriminations than when they receive information about a single cue alone. Such redundant conceptual information may be more salient than non-redundant information, which could better recruit attention and result in more precise learning and remembering than when such information is presented through only one cue.