If your data cannot leave your institution — and often it cannot — you can still get a read on it. Type five numbers from your Cell Ranger summary. Everything is computed in your browser; nothing is uploaded, stored or logged. If you can share a file, the full report is here instead.
Mitochondrial content is tissue-dependent: 5% is a reasonable ceiling for blood, and deleting everything above 5% in heart or liver removes the cell types you came for. Doublet rate scales with loading — roughly 0.8% per 1,000 cells recovered on droplet platforms — so a 10,000-cell run carries about 8% doublets, which a gene-count ceiling will not catch. Saturation tells you whether more sequencing would still buy genes. The long version, with what to use instead of fixed cut-offs.