Here's how to calculate your conversion rate:

For Email Marketing:
Conversion Rate = Total sales / Total emails sent * 100
Note: Industry average email conversion rates range between 1% to 3%

For PPC (Pay Per Click):
Conversion Rate = Total sales / Total clicks * 100
Note: Industry average PPC conversion rates range between 5% to 15%

For Search Engine traffic:
Conversion Rate = Total sales / Total visits generated by a search for target keyword * 100
Note: Industry average organic search engine conversion rates range between 3% to 7%

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Use web analytics software to effectively measure hits and conversions on your website. Remember that anything not measured will continue to deterioriate over time.

Note: All industry averages have been calculated in an environment where traffic is directed to a relevant landing page

http://www.google.com/analytics/index.html

Sophisticated. Easy. Free.

Google Analytics lets you measure website conversions for PPC campaigns, Email campaigns and any other form of online marketing campaign.