Ammunition, often shortened to ammo, is an important gameplay mechanic in the Ratchet & Clank series. Ammunition is required for most weapons to be used, and thus without ammo for a specific weapon, the player character would have to resort to a different one. All playable characters possess a melee weapon that does not require ammo, that being the iconic OmniWrench for Ratchet, or Clank's fists. Other weapons like the Walloper, Morph-o-Ray, Sheepinator, or Suck Cannon required no ammo at all, with the latter producing its own from sucked-up enemies.
Ammo is bought from vendors (or if available, a Gadgetron Personal Delivery Assistant), with each company selling ammo for its own weapons, and sometimes competitor's weapons' ammo as well. As ammo requires bolts, with the Zodiac's ammo costing 10,000 bolts each, there is an incentive to avoid wastefully spending any without cause. Ammo could also be found in ammo crates, with the original Ratchet & Clank supplying the player with unique ammo cases for each weapon. Notably autonomous weapons like the Synthenoids and Shield Charger's ammo could never be found in chests, forcing the player to use these sparingly.
In Going Commando, and Up Your Arsenal, ammo casings all shared the same design, but were still keyed to a specific weapon. Deadlocked was the only game in which ammo both shared the same design and could be used to refill any weapon, thanks to the self-adjusting modules reading your armor sensors, and subsequently changing to the ammo you need. In Size Matters and onwards, ammo casings all shared the same design, except for color and icon variations, to more easily distinguish between what kind of ammo was available for free.
Enemies in Deadlocked also often dropped ammo upon being destroyed. Ammo Pads replaced ammo crates in All 4 One, dispensing ammo to all players if anyone stepped on it.