New software is described that is designed for easy visualization and treatment of stepwise demagnetization of the natural remanent magnetization measured along sediment cores with pass-through magnetometers. The software displays demagnetization diagrams (Zijderveld plots) at successive horizons for any depth interval selected by the user. Paleomagnetic directions are automatically calculated using principal component analysis, with an anchored or a free origin. The demagnetization steps to be considered for the diagram visualization and paleodirection calculations are selected by the user. Maximum angular deviation angles and median destruction fields are also calculated. All the results are stored in a single data sheet, which can be easily exported. Demagnetization diagrams can be printed and copied. This Microsoft Excel software can be used by PC or Macintosh microcomputers.