Keyword difficulty is a score that estimates how hard it would be to rank on the first page of Google for a given keyword. Most SEO tools show it as a number from 0 to 100, with higher meaning harder.
It's a helpful shortcut when you're sorting through hundreds of keyword ideas. It's also an estimate built on each tool's own formula, so it works best as a starting point for your judgment, not a replacement for it.
What is keyword difficulty?
Keyword difficulty (often shortened to KD) is a third-party metric that rates the competition for a keyword based on the pages that currently rank for it. Semrush describes it as a measure of how difficult it is to earn a top position for a specific keyword.
Google doesn't publish a keyword difficulty score, and it isn't something Google uses to rank pages. It's a planning tool created by SEO software companies, which is why the same keyword can get very different scores in different tools.
Why keyword difficulty matters
During keyword research, you'll find more opportunities than you could ever cover. Difficulty helps you sort them. Paired with search volume and business value, it tells you where you can realistically win soon and where you'll need a longer runway.
For newer or smaller sites, this matters a lot. Going straight after highly competitive head terms can mean months of work with little to show for it. Starting with lower-difficulty, high-relevance topics builds traffic and topical authority you can grow from.
It also helps set expectations with stakeholders. A high-difficulty target is a signal that you'll likely need strong content, links and patience.
How keyword difficulty is calculated
There's no industry standard. Each tool uses its own inputs and weighting, and most don't publish full formulas. A Search Engine Land guide to keyword difficulty compares several approaches. Here's how a few major tools describe theirs.
Ahrefs
Ahrefs looks at the top 10 ranking pages for a keyword and counts how many unique websites link to each one, according to its keyword difficulty explainer. More linking domains across those pages means a higher score. It's essentially a backlink-based measure of the competition.
Semrush
Semrush says its score analyzes the top 10 results along with several factors, including referring domains, the Authority Score of ranking sites, search volume, SERP features and whether the keyword is branded. It groups scores into bands from "very easy" (0-14) up to "very hard" (85-100).
Moz
Moz's score roughly corresponds to a weighted average of the Page Authority of the top 10 results, adjusted using Domain Authority and other factors and accounting for projected click-through rate, as described in the Search Engine Land guide.
Because the methods differ, scores don't line up. Ahrefs' own article shows one keyword scoring anywhere from the 40s to the 70s depending on the tool. That's why you should pick one tool per project and compare keywords within it.
Keyword difficulty in practice
Imagine a hypothetical project management startup with a young website. Its keyword list includes "project management software" (very high difficulty), "project management software for architects" (moderate) and "how to run a project kickoff meeting" (low).
A practical plan starts with the low and moderate terms. The kickoff guide is a helpful, linkable resource that fits the product. The architect page targets a niche where the product has a real angle. Over time, those pages earn links and visibility, and the team can revisit the broad head term with a stronger site behind it.
Before committing to any of them, the team searches each keyword and looks at what ranks. A moderate score might hide outdated or thin pages that are easy to beat. A low score might hide a results page dominated by big brands with exactly the right content.
How to use keyword difficulty well
- Use it to compare, not to decide. Sort and shortlist with KD, then make the final call by looking at the actual results.
- Check the SERP manually. Ask whether the top pages truly match the search intent, how recent and thorough they are, and whether smaller sites are ranking. Those are signs of an opening.
- Factor in your own site. KD reflects the competition, not your strengths. A site with deep topical coverage and a solid link profile can compete for higher scores than a brand-new site. Some tools, like Semrush, also offer a personalized difficulty score based on your domain.
- Balance your portfolio. Mix quick wins with longer-term targets so you see progress while building toward bigger goals.
- Weigh business value heavily. A hard keyword that drives sales can be worth the effort. An easy one that brings the wrong audience isn't.
- Use long-tail keywords to get started. More specific queries tend to be less competitive and closer to a decision.
Common mistakes with keyword difficulty
Treating it as a Google metric. It isn't one. Google ranks pages on relevance, quality and many other signals, not on a tool's KD score.
Comparing scores across tools. A 40 in one tool and a 40 in another don't mean the same thing.
Avoiding every high score. If a keyword is central to your business, it may be worth a long-term plan even if it's tough today.
Assuming low means easy. A low score doesn't guarantee a ranking. You still need a page that serves the searcher better than what's there.
How Butter approaches keyword difficulty
At Butter, we use keyword difficulty as a filter, then look at the real results page before choosing a target. We consider the client's current authority, how well the ranking pages actually answer the query, and how closely the keyword ties to revenue. On the GEO+SEO plan, that shapes which of the eight monthly articles we prioritize, while the monthly backlink and on-page work help pages compete for tougher terms over time. We don't promise rankings for any keyword, hard or easy.
Frequently asked questions
What is a good keyword difficulty score?
It depends on your site. Newer sites usually do best starting with low to moderate scores, while established sites can aim higher. Always confirm by looking at the actual search results.
Why does keyword difficulty differ between tools?
Each tool uses its own formula and data, such as backlinks, authority scores or SERP features. There's no standard, so pick one tool and compare keywords within it.
Does Google use keyword difficulty?
No. Keyword difficulty is created by SEO software companies to help with planning. Google doesn't publish or use a KD score.