When looking at your Marketing Dashboard, you know the various lead sources are not easy to compare like apples to apples. For each lead channel you’ll have to account for:
The biggest difference though is how you think about the cost of the various lead channels. What’s the direct cost (advertising, staffing your online chat, the price of the booth at a trade show) or indirect cost (your all up team payroll, the overhead of your company's benefits, the investment in branding and brand awareness that’s not unique for a specific lead channel). To allow you to benchmark and optimize your various lead sources based on ROI, here’s what I recommend you do to calculate Cost-per-lead:
Review weekly, and learn from the cost of your different lead sources. If your Leadership team requires you to report monthly (vs. weekly or quarterly) you can just use an average of your weeks passed to calculate your ROI per channel. While the comparison of a 4 week month vs. a 5 week month will not be 100% accurate, it still allows you to do meaningful comparisons and show trends.