|Japanese (base text)||
A Pendulum Scale (Japanese: ペンデュラムスケール Pendyuramu Sukēru, abbreviated
Pendulum Scales are used in Pendulum Summoning. If there is a Pendulum Monster in both of the two Pendulum Zones, once per turn monsters in the hand and/or Pendulum Monsters that have been sent face-up to the Extra Deck can be Pendulum Summoned as long as their Levels are in between the Pendulum Scales of the two monsters exclusively. (Therefore, monsters cannot be Pendulum Summoned if the monsters in the two Pendulum Zones have the same Scale, or Scales that are only one number apart.) In the anime, the Pendulum Scale appears as a glowing number below the Pendulum Monster when it is in the Pendulum Zone.
A monster's Pendulum Scale seems to have some link to its Level, with higher-Level monsters tending to have lower Scales. Additionally, since most Pendulum Monsters released to date don't have a Scale equal to their Level/Rank, this means that those monsters can be potentially Pendulum Summoned using another copy of themselves.
As with Levels, Ranks, ATK, and DEF, there appear to be some unofficial conventions that govern how high or low a monster's Pendulum Scale values may be. A monster's Pendulum Scales may be as low as 2 or as high as 7 in normal cases; having a Scale of 1 or lower or a Scale of 8 or higher may require that the monster's Pendulum Effect have negative effects or conditions that restrict its use and cannot be negated.
As with all four of the above, a monster's Pendulum Scale may change from its printed number during a Duel due to other card effects. Currently in the OCG/TCG, a monster's original Pendulum Scale may range from 0 to 13; no effects can currently reduce a Pendulum Scale to below 1, but effects can theoretically raise the Pendulum Scale to any number above 10 (e.g. "Yosenju Shinchu R", "Performapal Guitartle"). Currently there are no Scale 11 monsters in the TCG/OCG; they only exist in the anime, though the Pendulum Effect of "Yosenju Shinchu R" specifically mentions "Scale 11".
- Until the release of Booster Pack Maximum Crisis in 2017, it was impossible to Pendulum Summon Level 1, 10, 11 and Level 12 monsters through normal means, as there were no Scale 0 or Scale 13 Pendulum Monsters (nor Scale 11 and 12, but Scale 11 is still non-existant).
- When Pendulum Monsters were first introduced, it was said in official explanations that monsters placed in the left Pendulum Zone would have their blue Pendulum Scale become active, while monsters placed in the right Pendulum Zone would have their red Pendulum Scale become active, implying that it was initially planned to make Pendulum Monsters with mismatched Scales. However, such Pendulum Monsters were never released, nor cards with effects that could cause a single monster to have two different Pendulum Scales. As such, this detail currently has no application in gameplay.
- yugioh-card.com/en Learn How to Pendulum Summon Tutorial Video (english)