How these numbers are calculated
Engagement rate is total engagements (likes + comments + shares/saves) divided by your follower or reach count. Estimated media value treats your reach as equivalent ad impressions, valued at the CPM you specify (reach ÷ 1,000 × CPM) - a common way to express "what this exposure would have cost to buy as advertising." If you enter a campaign cost, ROI compares that estimated value against what you actually spent.
Why media value is a comparison framework rather than real revenue
Media value is a comparison framework, not real revenue - it estimates what the reach would cost to buy as ads, not money the post actually generated. Use it to compare campaigns consistently, not as literal income, since no sale or conversion data factors into the calculation at all.
Why the campaign cost field is optional rather than required
Organic posts (ones you didn't pay to promote) have no campaign cost to compare against, so this tool treats that field as optional and simply skips the ROI card entirely when it's left blank - showing you the engagement rate and estimated media value on their own, which still works as a useful comparison metric for unpaid content.
Why picking the right CPM for your situation matters more than any other input
Every other number here is objective (your actual follower count, actual likes, actual comments) but the CPM is an assumption you supply - and since media value is directly proportional to it, a CPM that doesn't reflect your actual platform and niche will meaningfully skew every other number this tool calculates from that point on.