One free interactive tool — the same arithmetic as the worked guides, with your numbers in the inputs. Every tool shows its formula, and every pre-filled default is a labeled hypothetical example, never a benchmark or a vendor claim.
What is our visitor identification match rate, really?
Compute your visitor-identification match rate from your own traffic: pick one of the four denominators, get the raw rate, subtract false positives with a precision sample, and see how many sessions to ground-truth next.
Each calculator implements a formula from a worked guide, where the same arithmetic is written out step by step with its assumptions and failure modes. If a number surprises you, read the paired guide linked on the tool’s page — then re-run the tool with numbers from your own analytics property, not a vendor dashboard.