A Simple Formula to Judge If a Keyword Is Worth Building For

Picking the wrong keyword wastes months. Picking keywords by gut feeling is how that happens. Here is a simple, homemade metric that turns keyword selection into arithmetic: kdroi, short for keyword difficulty return on investment.

(Figures and case details in this article are as reported in the source material and have not been independently verified.)

1. Two beliefs before the formula

The formula rests on two premises. First, the closer a keyword is to money, the more it is worth: a keyword whose searchers are ready to spend beats one whose searchers are just browsing, even at the same search volume. Second, traffic from developed countries is commercially worth more than traffic from elsewhere, because advertisers there bid higher. Everything below follows from these two ideas.

2. The kdroi formula

kdroi = monthly search volume x CPC / keyword difficulty (KD)

• Volume: how many times the keyword is searched per month.
• CPC: the average price advertisers pay per click on that keyword — the best available proxy for “how close this keyword is to money”.
• KD: the keyword difficulty score from a tool like Semrush — the cost side of the equation.

Compute kdroi for every candidate keyword, sort from high to low, and the words at the top are the most worth building for. Feeling is replaced by a ranked list.

3. How to run it in Semrush, step by step

1. Start from a seed word. In the walkthrough below, the seed is “Calculator”.
2. Filter the keyword list: monthly volume at least 600, KD between 0 and 29, CPC above 0.1, and exclude “near me” type queries.
3. Export the result as a spreadsheet. In the reported example this left 357 candidate keywords.
4. Keep four columns: Keyword, Volume, KD, CPC. Add a fifth column with the formula =Volume*CPC/KD and fill it down for every row.
5. Sort the whole table by the new kdroi column, descending.

4. What the ranking looks like

In the reported run, the top-ranked keyword was “audiobook speed calculator”: 1,600 monthly searches, KD 7, CPC USD 13.9, giving a kdroi of 3,177.14. The rest of the top ten were dominated by calculator-style tool keywords — audiobook calculator (2,468.00), neb tm calculator (1,645.58), shsat score calculator (1,026.19), construction loan calculator (806.14), paycheckcity calculator (792.00), sailrite fabric calculator (749.65), virginia paycheck calculator (735.52), oregon paycheck calculator (729.93). The pattern is clear: tool keywords with high CPC and moderate difficulty float to the top.

The “sweet spot” the formula reveals is exactly that combination: high CPC (close to money) plus low KD (cheap to rank). That intersection is where the return per unit of effort is highest.

5. The formula is step one, not the whole job

A high kdroi means the keyword is worth pursuing — it does not mean you can skip the rest of the work. Before building any page, analyze the search intent behind the keyword first: what does the searcher actually want to see? Only after intent is clear should you start making the page. Selection by formula, execution by intent.

Series: Overseas Website Building