Link budget calculator: how many links, and what they cost

How the estimate works

• Links are weighed, not counted. A referring domain counts as 1 + its authority ÷ 25. At authority 0 it counts 1, at 25 it counts 2, at 75 it counts 4.
• Their link strength is their number of good referring domains times the weight of their median domain. Your existing domains are weighed the same way.
• Links needed is the missing strength divided by the weight of one offer at your average DR.
• Estimated effect follows a curve with diminishing returns: ln(1 + your strength) ÷ ln(1 + their strength). For a site with no links the first ones move it most, which is why a small budget can cover a large part of the distance. If you already have links, the effect includes them.

What it leaves out

• It is an estimate, not a ranking forecast. It describes how close you get to a competitor's link strength. Rankings depend on far more than links.
• One median stands in for every domain. The app weighs each referring domain on its own and prices each real offer, cheapest first, with surcharges. Its answer for the same competitor will differ from this one.
• DR and authority are different scales. Marketplaces advertise Ahrefs DR; backlink data uses its own authority. Treating them as one is an approximation, so the "worth" factor is indicative.
• Garbage in, garbage out. If the competitor's count still contains spam or a bought link network, every number here is too high. Clean it first: see Backlink gap analysis and How to spot a link network.
• It doesn't say you should buy links. Google's spam policies name buying links for ranking purposes as link spam, and expect paid links to carry rel="sponsored".

Where the example values come from

Nowhere: they are invented round numbers to show how the calculator works. Replace them with your own. A worked calculation with real marketplace prices is in What does link building cost?