Standard card sizes vary by use: poker 2.5×3.5 in, tarot 2.75×4.75 in, US business 3.5×2 in. Greeting cards: A2 4.25×5.5, A6 4.63×6.25, A7 5×7. Postcards 4×6–6×11. Use proper bleed & safe zones to print cleanly and meet standard rules.