Once you have collected and analyzed your data, you can calculate your webinar ROI across multiple channels using the formula: ROI = (Revenue - Cost) / Cost x 100%. For example, if you spent $1,000 on creating and promoting your webinar and generated $5,000 in sales from it, your ROI would be 400%. However, this formula may not capture the full value of your webinar, so you should also consider other factors such as lifetime value, customer acquisition cost, customer retention rate, and customer satisfaction and referrals. To estimate these factors and adjust the ROI formula accordingly, you can use tools like Excel, Google Sheets, or ROI calculators. Based on this calculation, you can identify which channels and strategies are working well and which ones need improvement. You can also test different variables such as webinar title, description, image, date, time, duration, content format, delivery offer call to action and follow-up promotion targeting and segmentation using tools like Google Optimize Unbounce or Instapage for A/B tests to optimize performance.