Step one, traffic per link per month. The model takes the average DR you entered, multiplies by 0.4, and applies a floor of one visit. A DR45 link is therefore assumed to send 18 visits a month. This is the assumption doing the most work and the one with the least evidence behind it, and you should override it mentally if you know your own numbers.
The output is gross return, not net. Subtract your real cost per link, including labor, before you call it ROI.
Step two, monthly referral traffic. Links per month multiplied by that per-link figure. Fifteen links at DR45 gives 270 visits a month. Note this treats every link as equally valuable at the same DR, which is wrong in a specific direction: a link in the body of a well-trafficked article is worth many times one in a footer or a resource page nobody visits.
Step three, lifetime traffic. Monthly traffic multiplied by average link lifetime in months. At 18 months, those 270 visits become 4,860. This is where the number starts to look impressive, and it is also where link loss does its damage, because the whole figure scales linearly with an input most people guess at optimistically.
Step four, the two value outputs. Estimated lifetime revenue takes lifetime traffic, applies your conversion rate, then your average order value. Equity value takes the monthly traffic, multiplies by your traffic value per visit, then by lifetime months, which gives you the cost of buying that traffic instead. Both are simple multiplication. Neither includes any ranking effect, and neither subtracts what you spent.
That last point is worth sitting with. This tool calculates gross return, not net. To get to actual ROI you need to subtract your fully loaded cost: placement fees, content production, and the hours your team spent. A model that skips the cost side is how link building gets approved and then quietly underdelivers.