The hand size limit (手札制限枚数 Tefuda Seigen Maisū, hand limit number) refers to the number of cards a player may keep in their hand at the end of their turn. If, during the end of a player's own End Phase, they have more than that number, they must choose cards to discard until they drop down to that number.

The usual hand size limit during a Duel is six. A small number of cards have effects that can change this limit:

  • "Hieroglyph Lithograph": This card requires a cost of 1000 Life Points to activate, and raises the user's hand size limit to seven for the rest of the Duel.
  • "Enervating Mist": As long as this card stays on the field, the opponent's hand size limit is lowered to five.
  • "Infinite Cards": This card removes the limit on both players' hand sizes, as long as it remains on the field.
  • "Silent Wobby": This lowers its own controller's hand size limit to three, as long as it remains on the field. Its other effect is designed to help give control of it to the opponent.
  • "Finite Cards": This lowers both players' hand limits to three while it remains on the field.
"Finite Cards" can prove to be most useful to a player with preventing their opponent from summoning Exodia The Forbidden One as it prevents each player from having more than three cards in their hands and a player must have all five pieces of Exodia in their hand in order to summon The Forbidden One. "Infinite Cards" can prove to be useful for a strategy involving the Egyptian God Card, Slifer The Sky Dragon. In accordance with its special ability, Slifer's attack points determine on the number of cards its owner is holding multiplied by 1000. With the six card hand limit Slifer's attack points can't be stronger than 6000 with the discard regulation in place, but with Infinite Cards the hand limit is removed, allowing players to hold as many cards as they wish; thus, Slifer's attack points can be even higher than 6000.