Conversion rate is the percentage of a defined audience that completes a desired action during a defined period. The formula is simple, but the result depends on what counts as a conversion and what population is used as the denominator.
Basic Formula #
Conversion rate (%) = (number of conversions ÷ number of eligible visitors or sessions) × 100
Worked Example #
If a landing page receives 2,000 eligible sessions and produces 80 completed lead forms, the session-based conversion rate is (80 ÷ 2,000) × 100 = 4%.
Choose the Right Denominator #
Visitor-based rates use unique users; session-based rates use visits; click-based rates use ad clicks or CTA clicks. These answer different questions. State the denominator consistently and avoid comparing rates calculated using different methods.
Useful Related Metrics #
- Form completion rate: completed forms ÷ form starts × 100.
- Checkout completion rate: completed purchases ÷ checkout starts × 100.
- Lead-to-customer rate: customers acquired ÷ leads generated × 100.
Common Measurement Mistakes #
Do not count duplicate events as separate conversions without intent, mix users and sessions, change the date range mid-comparison, ignore tracking failures or treat all leads as equally valuable. Annotate campaigns and site changes that may affect results.
Use the Metric Carefully #
A higher conversion rate can be misleading if traffic quality falls or average order value declines. Review revenue, margin, qualified leads and customer outcomes alongside the rate.
Related Topics #
Read Conversion Funnel Analysis and CRO Tools and Reporting.
