# Semrush vs Similarweb: keywords against traffic estimates

These two are compared because both will show you a number next to a rival's domain. They are not the same number. Semrush estimates what a site earns from search, query by query. Similarweb estimates how many people visit it at all, from every channel. Decide which question you have before you decide which to pay for.

Updated 2026-09-15 · Source: https://porteur.ai/compare/semrush-vs-similarweb

## Two different questions

- What does this rival rank for, and which of their pages earns it? That is Semrush, and the answer is a list of queries and pages you can act on.
- How big is this company's audience, where does it come from, and how engaged is it? That is Similarweb, and the answer is a shape of visits across channels and countries.
- What do my own pages earn? Neither. That is Search Console and your analytics, free and exact.

> A founder choosing what to write next needs the first. A founder writing a fundraising deck or sizing a market needs the second.

## Where each number comes from

Neither company can see another site's analytics. Both model, from different raw material, which is why the outputs differ in kind as well as in value.

- Semrush builds from its own view of search: a large set of tracked queries, the results pages for them, and a model of what a position on a query is worth in clicks. Its traffic figure is search traffic, estimated, not total visits.
- Similarweb models total traffic from panels, data partners and public sources, then extrapolates. It reports visits, the split by channel, geography, audience and engagement.
- Both get more accurate the larger the site. For a small product with a few thousand visits a month, both are rough, and Similarweb explicitly becomes rough at the small end.
- A limited free version of Similarweb exists, which is enough to see the shape of a large site.

## Side by side

| Question | Semrush | Similarweb |
| --- | --- | --- |
| What it estimates | Search visibility and search traffic | Total visits across channels |
| Query-level detail | Yes, the keywords and the pages | No |
| Channel split | Search, paid and organic | Direct, search, social, referral, mail, display |
| Geography and audience | By market, for search | Its speciality |
| Your own site | Audits, tracking, keyword research | Not an audit or keyword tool |
| Small sites | Thin, because few queries are tracked | Rough, because the panel sees few visits |

## Why they disagree about the same site

Put one domain into both and you will get two numbers that do not reconcile. That is expected, and knowing why stops you trusting the wrong one.

- They measure different things: one search only, the other every channel. A site with a newsletter and a big social following will look far bigger in Similarweb.
- They model from different raw material: a query index against panels and partners.
- Coverage differs by market and by language. Both are strongest where their data is thickest.
- Neither sees brand-new pages quickly, and both lag reality by weeks.
- Neither can see the site's own analytics, which is the only exact figure and belongs to whoever owns the site.

> Use an estimate to compare two sites in the same tool, on the same day. Never quote one as a fact about a company you do not own.

## Which to open, by the question

| You want to know | Open |
| --- | --- |
| Which searches my rival wins, and with which page | Semrush |
| Whether a market is big enough to enter | Similarweb |
| What to write next quarter | Semrush |
| Where a competitor's visitors come from | Similarweb |
| Which of my pages need work | Neither: Search Console |
| Whether my own traffic is growing | Neither: your analytics |

## What neither one tells you

- Your own impressions, clicks, positions and indexing state. Search Console has them, free, and they are Google's own figures.
- What visitors did after they landed. That is your product analytics, joined to the landing page.
- Revenue. No external tool has ever seen a payment.
- Why a rival ranks. The tools show the what; the reading of the page and the links is still yours.

## When a founder needs either

Most small products need neither in the first months, and then need one of them for a specific week.

- Before writing a content plan: a keyword suite, for one or two months, to size the searches and see who holds them.
- Before a fundraise or a market sizing: a traffic estimator, to describe the shape of the market in numbers an investor recognises.
- Before a competitive launch: both for a week, then neither.
- For the routine month: Search Console, your analytics, and the hour you would have spent in a dashboard.

## How to sanity-check an estimate in five minutes

1. **Look up a site you own** Put your own domain into the tool and compare its estimate with your analytics. You now know which direction that tool errs in, for a site your size.
2. **Look up a site you know well** A partner, a former employer, anywhere you have seen the real numbers. Two data points are enough for a rule of thumb.
3. **Compare rivals, never absolutes** Rival A against rival B inside one tool on one day is a fair comparison. Either number quoted alone is not.
4. **Check the market coverage** If your buyers are outside the tool's strongest markets, halve your confidence again.
5. **Write down the date** Estimates are revised, models change, and a screenshot without a date is worthless in three months.

## The tools compared

### Semrush

Search research: the queries a site ranks for, the pages that earn them, and the work to do on your own site. (semrush.com)

Good at: Keyword Magic Tool for grouped ideas; Competitive research on rivals' queries and pages; Position Tracking for a watch list; Site Audit on your own site; Backlink Analytics.

Choose it when Your question is which searches to target and who currently holds them.

Not for: Sizing a whole market's traffic across every channel.

### Similarweb

Estimating total traffic and audience for any site, across every channel. (similarweb.com)

Good at: Visits and channel split for a domain; Geography and audience overlap; Comparing several competitors at once; Market and industry views; A limited free version for a quick look.

Choose it when You are sizing a market or describing a competitor's audience rather than planning pages.

Not for: Keyword research, audits or anything about your own site's pages.

**Verdict.** Take Semrush when the output you need is a list of searches and pages to act on, and Similarweb when you need the shape of a market or a competitor's audience for a deck. Both are models, both are rough for small sites, and neither should be quoted as a fact about a company you do not own. Check either against a site whose real numbers you have seen before you trust its scale, and keep Search Console as the only exact figure for your own pages.

## Questions

### Which is more accurate, Semrush or Similarweb?

They estimate different things, so neither is more accurate than the other in general. Both improve with the size of the site and both are rough for small sites. The only exact figures about a site belong to whoever owns it.

### Can I see a competitor's real traffic?

No. Every third-party figure is a model built from panels, partners, public data or a query index. Treat them as comparisons between sites inside one tool rather than as measurements.

### Does Similarweb do keyword research?

It is not built for the keyword and audit work you do on your own site. It reports visits, channels, geography, audience and engagement for any domain. For query-level research, a search suite is the right tool.

### Is there a free way to estimate a competitor's traffic?

Similarweb has a limited free version that shows the shape of a large site. Search suites show some data free or in trials. For small sites all of them are rough, and the cheapest honest answer is to read the site and the results pages it appears on.

### Which one should a small SaaS buy?

Usually the search suite, and only while planning content, because its output is a list of queries and pages you can act on. A traffic estimator is worth a month when you need to describe a market rather than change your own site.

## Read next

- [Similarweb alternatives](https://porteur.ai/alternatives/similarweb-alternatives): Use Similarweb for big-site estimates. For small products, switch by job: Semrush or Ahrefs for search estimates, SpyFu for history, Search Console for truth.
- [Ahrefs vs Semrush for a small product site](https://porteur.ai/compare/ahrefs-vs-semrush): Choose Ahrefs if links and Site Explorer matter most, Semrush if you need a broad keyword and marketing suite. Here is how to decide quickly.
- [How to check organic traffic: yours exactly, a rival’s roughly](https://porteur.ai/guides/how-to-check-organic-traffic): See your exact Google clicks in Search Console, your organic sessions in GA4, and a rival’s rough traffic with estimator tools. What to trust and why.
- [How to analyse a competitor’s keywords, with and without a tool](https://porteur.ai/guides/analyze-competitor-keywords): A fast way to find competitor keywords you can win: read their sitemap and titles, then confirm gaps with a tool and pick only queries you can match.
- [Google Keyword Planner vs the paid keyword tools](https://porteur.ai/compare/keyword-planner-vs-keyword-tools): Where every search volume comes from, why the Planner shows ranges, what the paid tools add, and how to use the free one without being misled.
- [Keyword search volume: where the number comes from and how far to trust it](https://porteur.ai/guides/keyword-search-volume): What search volume really is, how tools make the number, where it misleads, and how to use it to rank pages against each other, not as a forecast.
- [Competitor research for a founder: one afternoon, no subscription](https://porteur.ai/guides/seo-competitor-research): Find who actually beats you in search, read their sitemaps, titles and links with free tools, and finish with a one-page plan you will act on.
- [Semrush vs Ahrefs vs Moz: the three suites, side by side](https://porteur.ai/compare/semrush-vs-ahrefs-vs-moz): The three suites on the criteria that decide it: link index, keyword data, audits, tracking and teaching. Who each is for, and the free path first.

Paste your URL for a free check that reads your own site and the searches around it, with the rivals who hold them, in about thirty seconds. No estimate of anyone's traffic, three findings you can act on. Free check: https://porteur.ai/