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).
Matilda has been climbing in recent years. All-time it's been given to 48,245 U.S. babies, the 760th most common name by sound today, peaking at 897 in 2025, with 897 in 2025.
By sound, Matilda also includes the spellings Mathilda, Matilde.
Source: U.S. Social Security Administration, “National data” baby-names files (1880–2025).