Y100

Y100 or Y-100 may refer to:
 * Yttrium-100 (Y-100 or 100Y), an isotope of yttrium

Radio stations branded "Y100"

 * KCYY in San Antonio, Texas
 * WHYI in Miami, Florida
 * WNCY in Green Bay, Wisconsin
 * WPLY, former station in Philadelphia, Pennsylvania
 * WSGY, former station in Tifton, Georgia
 * WXYY, former station in Rincon, Georgia
 * WZJZ in Ft. Myers, Florida