Conversion
Conversion Rate
Why signup-to-paid conversion is meaningless without cohort context — and the definition we recommend.
Signup-to-paid conversion is the most-quoted, least-useful metric in SaaS. Reported as a single lifetime number, it flatters bad months and punishes good ones. It mixes cohorts that had fourteen days to convert with cohorts that had fourteen months.
The fix is to always report conversion as a cohort curve. Take everyone who signed up in a given week; measure what percentage had converted by day 7, 14, 30 and 90. Compare cohorts to each other, not to a rolling average.
Then, and only then, will your conversion rate tell you whether last month's landing-page change actually worked.