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).
April is now well below its former popularity. All-time it's been given to 246,740 U.S. babies, the 940th most common name by sound today, peaking at 11,625 in 1980, with 566 in 2025.
By sound, April also includes the spellings Apryl.
Source: U.S. Social Security Administration, “National data” baby-names files (1880–2025).