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The 7×57mm Mauser (designated as the 7mm Mauser or 7×57mm by the SAAMI and 7 × 57 by the C.I.P. is a first-generation smokeless powder rimless bottlenecked rifle cartridge. It is known as .275 Rigby in the United Kingdom. It was developed by Paul Mauser of the Mauser company in 1892 and adopted as a military cartridge by Spain in 1893. It was subsequently adopted by several other countries as the standard military cartridge, and although now obsolete as a military cartridge, it remains in widespread international use as a sporting round. Many sporting rifles in this calibre were made by British riflemakers, among whom John Rigby was prominent; and, catering for the British preference for calibres to be designated in inches, Rigby called this chambering the .275 bore after the measurement of a 7 mm rifle's bore across the lands.

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