WPI is the abbreviation of:
- Worcester Polytechnic Institute, a private university in Worcester, Massachusetts, USA.
- Short use of DWPI ( Derwent World Patents Index)
- Whey protein isolate, a dietary supplement created by filtering milk protein
- Whittemore Peterson Institute, performs research into chronic fatigue syndrome
- Wholesale price index, the price of a representative basket of wholesale goods
- Wilayah Pembangunan Iskandar
- Windows Post-Install Wizard (or WPIW), a software application for choosing and installing multiple Windows programs
- Winning Percentage Index, a measure of a team's strength. Used in some locations to seed bracketed tournaments
- Work Personality Index
- Worker-Communist Party of Iran (Persian: حزب کمونیست کارگری ایران) founded 1991, a political party that seeks the revolutionary overthrow of the Islamic Republic of Iran and the establishment of a 'Socialist Republic' in its place
- World Policy Institute, a research and education policy center in New York City
- World price index, the price of a representative basket of goods available in the top 15 global economies. Used for monthly Purchasing Power Parity calculations.
- Wraps Per Inch, a method of measuring the weight of yarn