Solid line = floor (spellings that unambiguously belong to the group). Shaded band up to the dashed edge = ceiling (the most it could reach if every ambiguous spelling counted here).
Caleb is down from its peak but still widely used. All-time it's been given to 411,854 U.S. babies, the 77th most common name by sound today, peaking at 15,137 in 2002, with 6,360 in 2025.
By sound, Caleb also includes the spellings Kaleb.
Source: U.S. Social Security Administration, “National data” baby-names files (1880–2025).