What size is Nike US 12 in Converse?

About Converse US 11.5 (EU 45.5), matched by ~28.8 cm. Then adjust for the specific model.

Is a Nike 12 the same as a Converse 12?

Not always. Labels can map to different foot lengths — use cm, then model fit.

Brand-to-brand size at a fixed US label — matched by foot length (cm), not guesswork.

Nike US 12 maps to about 28.8 cm on that brand’s chart. The nearest Converse row at that length is US 11.5 / EU 45.5.

Same chart cm can still feel different on foot. Read the guides:

Nike: Air Force 1 '07 (runs big) · Dunk Low (true to size) · Pegasus 41 (true to size) · Vomero 5 (true to size) · Air Max 90 (true to size)

Converse: Chuck Taylor All Star High (runs big) · Chuck 70 High (runs big)

What size is Nike US 12 in Converse?: About Converse US 11.5 (EU 45.5), via ~28.8 cm.
Where is the full size table?: Nike to Converse compare.