Primer-Coverage for Amplicon Sequencing (PCAS) is a comprehensive database that records CRs of the amplicon region and the coverage of primers and primer pairs in the SSU, LSU, and ITS regions. Our database provides a comprehensive collection of the CRs and the coverage analyses of 250 rDNA primers and 6251 primer pairs. With access to PCAS, researchers can make informed decisions and choose primers tailored for their research needs, ultimately enhancing the quality and interpretation of microbial community analyses.