Company and Nature of Business	9 Months Ended
Sep. 30, 2025
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Company and Nature of Business	Note 1. Company and Nature of Business Personalis, Inc. (the "Company" or "Personalis") develops, markets, and sells advanced cancer genomic tests and services. The services are used by pharmaceutical companies for translational research, biomarker discovery, the development of personalized cancer therapies, and for clinical trials. The clinical version of the tests are used by physicians to detect residual or recurrent cancer in patients, monitor cancer response to therapy, and uncover insights for therapy selection. The Company also provides whole exome and whole genome sequencing ("WGS") services for other diagnostic companies and population sequencing initiatives. The principal markets for the Company’s tests and services are in the United States and Europe. The Company is expanding its business model to offer genomic tests directly to cancer patients in a clinical setting. However, revenue generated from clinical patients was not significant for any periods presented in these consolidated financial statements. The Company was incorporated in Delaware in February 2011 and began operations in September 2011. The Company formed a wholly owned subsidiary, Personalis (UK) Ltd., in August 2013 and a wholly owned subsidiary, Shanghai Personalis Biotechnology Co., Ltd., which is referred to as “Personalis (Shanghai) Ltd” herein, in October 2020. The Company terminated its operations in China and completed the process of dissolving the Personalis (Shanghai) Ltd entity in February 2024. The Company operates and manages its business as one reportable operating segment, which is providing advanced cancer genomic tests and services for precision oncology applications, personalized testing, and other tests. The Company has incurred losses to date and expects to incur additional losses for the foreseeable future. The Company continues to invest the majority of its resources in the development and growth of its business, including investments in product development and sales and marketing efforts. The Company’s activities have been financed to date primarily through the sale of its equity securities and cash from operations.

Company and Nature of Business

9 Months Ended

Sep. 30, 2025

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Note 1. Company and Nature of Business

Personalis, Inc. (the "Company" or "Personalis") develops, markets, and sells advanced cancer genomic tests and services. The services are used by pharmaceutical companies for translational research, biomarker discovery, the development of personalized cancer therapies, and for clinical trials. The clinical version of the tests are used by physicians to detect residual or recurrent cancer in patients, monitor cancer response to therapy, and uncover insights for therapy selection. The Company also provides whole exome and whole genome sequencing ("WGS") services for other diagnostic companies and population sequencing initiatives. The principal markets for the Company’s tests and services are in the United States and Europe.

The Company is expanding its business model to offer genomic tests directly to cancer patients in a clinical setting. However, revenue generated from clinical patients was not significant for any periods presented in these consolidated financial statements.

The Company was incorporated in Delaware in February 2011 and began operations in September 2011. The Company formed a wholly owned subsidiary, Personalis (UK) Ltd., in August 2013 and a wholly owned subsidiary, Shanghai Personalis Biotechnology Co., Ltd., which is referred to as “Personalis (Shanghai) Ltd” herein, in October 2020. The Company terminated its operations in China and completed the process of dissolving the Personalis (Shanghai) Ltd entity in February 2024. The Company operates and manages its business as one reportable operating segment, which is providing advanced cancer genomic tests and services for precision oncology applications, personalized testing, and other tests.

The Company has incurred losses to date and expects to incur additional losses for the foreseeable future. The Company continues to invest the majority of its resources in the development and growth of its business, including investments in product development and sales and marketing efforts. The Company’s activities have been financed to date primarily through the sale of its equity securities and cash from operations.