Abstract: A centering tool for disposing and maintaining a basket sink strainer in concentric and superposed parallel relationships with respect to a sink drain hole for subsequent assembled securement of the sink strainer. The centering tool comprises a tubular spider of upper and lower horizontal arms, normal to each other, telescopically mounting extensible tubular elements that are adjustably positionable for contact with the lateral corners of the sink. An adapter member, depending from the center of the spider's lower arm, carries a pronged adapter element that complementally engages arcuate slots in the bottom well of the sink strainer. Vertically disposed tubular feet, depending from the arms, rest upon the bottom surface of the sink.