Brand-to-brand size at a fixed US label — matched by foot length (cm), not guesswork.
Two charts · cm matchJordan US 8 maps to about 25.4 cm on that brand’s chart. The nearest Nike row at that length is US 8 / EU 40.5.
Same chart cm can still feel different on foot. Read the guides:
Jordan: Air Jordan 1 High (true to size) · Air Jordan 4 Retro (true to size)
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)