Mantissa ( /mænˈtɪsə/) may refer to:

• Mantissa (logarithm), the fractional part of the common (base-10) logarithm
• Significand (also commonly called mantissa), the significant digits of a floating-point number or a number in scientific notation
• Mantissa (band)
• Mantissa (novel), a 1982 novel by John Fowles
• Mantissa College
• De anima libri mantissa, sometimes simply referred as Mantissa, treatise attributed to Alexander of Aphrodisias