.32 caliber is a size of ammunition, fitted to firearms with a bore diameter of 0.32 inches (8.1 mm).

.32 in caliber variations include:

• .32 ACP (Automatic Colt Pistol), a pistol cartridge
• .32-40 Ballard, an American rifle cartridge
• .32 H&R Magnum, a rimmed cartridge designed for use in revolvers
• .32 Long Colt, an American centerfire fire revolver cartridge
• .32 NAA, a cartridge/firearm system from North American Arms and Corbon Ammunition using a .380 ACP case
• .32 Remington, an American rifle cartridge
• .32 rimfire cartridge, chambered in revolvers and rifles in the late 19th and early 20th centuries
• .32 S&W, cartridge was introduced in 1878 for the Smith & Wesson model 11⁄2 revolver
• .32 S&W Long, a straight-walled, centerfire, rimmed handgun cartridge, based on the earlier .32 S&W cartridge
• .32-20 Winchester, the first small-game lever-action cartridge that Winchester produced
• .32 Winchester Self-Loading, an American rifle cartridge
• .32 Winchester Special, a rimmed cartridge created in October 1901 for use in the Winchester Model 94 lever-action rifle
• .327 Federal Magnum, a rimmed cartridge based on the .32 H&R Magnum with elongated case and higher pressure