ΔE 15.6, loose: different enough that you should pick on purpose. Cerulean Blue, Chromium is noticeably lighter, more saturated than Viking Blue.
Not as a straight swap; see the closer alternatives below. Loose match (ΔE 16). Cerulean Blue, Chromium is noticeably lighter, more saturated than Viking Blue.
The same difference applies the other way round: Viking Blue is noticeably darker, more muted.
ΔE is the colour difference between our two swatch estimates: under about 6 is close, over about 15 is loose. Real paints also differ in finish, coverage and how they thin, so test before you commit.
See Viking Blue on the colour wheel See Cerulean Blue, Chromium on the colour wheel
All matches: Viking Blue equivalents · Cerulean Blue, Chromium equivalents