Studies of calibration have shown that people's mean confidence in their answers (local confidence) tends to be greater than their overall estimate of the percentage of correct answers (global confidence). Moreover, whereas the former exhibits overconfidence, the latter often exhibits underconfidence. Three studies present evidence that global underconfidence reflects a failure to make an allowance for correct answers that are likely to result from mere guessing and can be eliminated by informing participants of the dubious normative status of estimates below 50% (i.e., chance). Previously reported discrepancies between global and local confidence, it is concluded, arise less from possible methodological artifacts in assessment of local confidence than from normatively inappropriate assessments of global confidence.