Historical Rules · 18 February 2022
Rule 108.2a
Official source text from the 18 February 2022 Rules release
Most Magic games use only traditional Magic cards, which measure approximately 2.5 inches (6.3 cm) by 3.5 inches (8.8 cm). Traditional Magic cards are included in players’ decks. Certain formats also use nontraditional Magic cards. Nontraditional Magic cards are not included in players’ decks. They may be used in supplementary decks. Additionally, they may be oversized, have different card backs, or both.