Share of Search: The Metric That Predicts Market Share

Most marketing metrics tell you what already happened. Share of search is one of the rare ones that tells you what's about to happen — and you can calculate it yourself, for free, in Google Keyword Planner, without a research budget. What share of search actually is Share of search is your brand's share of all the branded searches in your category. Take the total number of people searching for you and your named competitors by name over a period, and divide your number by the total. If you and three competitors get searched by name a combined 1,000 times a month, and 250 of those searches are for you, your share of search is 25%. That's it — no survey, no panel, no agency. It's built entirely from data Google already collects and already shows you for free through Keyword Planner. If you'd rather skip pulling the numbers yourself, you can see your share of search next to local competitors in a free automated report — but the manual version below is worth understanding even if you end up using the shortcut. Why this number predicts market share This isn't a metric someone invented because it sounded plausible. It comes from research by Les Binet, presented at the IPA's EffWorks Global conference in 2020. Binet tested share of search against actual market share across several categories — including automotive, energy, and mobile phones — and found a consistent pattern: when a brand's share of search rises, its share of market tends to follow, usually with a lag. For some categories, like cars, that lag ran close to a year — meaning share of search was showing a shift in market position before it showed up in sales figures. Binet's framing for the gap between the two is "Extra Share of Search" (ESOS) — when a brand's share of search runs ahead of its share of market, that gap tends to predict the market share is about to move up to close it, and vice versa. Follow-up research by James Hankins for the IPA, covering 30 case studies across 12 categories and seven countries, found share of search explained roughly 83% of the variation in a brand's market share — a strong enough relationship that share of search gets treated in marketing effectiveness circles as one of the few genuinely predictive, cheap-to-measure brand metrics available. Worth being precise about what this research actually covers: Binet's original work was done at the category level — national or regional brands in categories like cars and energy, not local businesses competing block by block. The same logic — more people searching for you by name relative to your competitors signals growing consideration, which tends to precede growing share — holds at the local level too, but it's a reasonable extension of the research, not a direct restatement of it. Treat it as a strong, well-grounded signal, not a guarantee specific to your category. A worked example Say you run a local moving company. You list four real competitors — the ones customers actually compare you against when they're getting quotes. Pulling 12 months of Keyword Planner data for all five business names gives you this: You: 320 searches/month averageCompetitor A: 590 searches/month averageCompetitor B: 210 searches/month averageCompetitor C: 140 searches/month averageCompetitor D: 90 searches/month average Total category search volume: 1,350. Your share of search: 320 ÷ 1,350 = 23.7%. Competitor A, by comparison, sits at 43.7% — nearly double yours, which tells you more about where you actually stand than "we're ranked #3 locally" does on its own, because it's measuring demand, not just where Google happens to place you today. Run the same calculation again next quarter. If your share climbs to 27% while Competitor A's slips to 40%, that's the "Extra Share of Search" dynamic from Binet's research in motion — your actual market position is likely starting to shift before it shows up anywhere else you'd normally look, like revenue or lead volume. Share of search vs. share of voice These two get used interchangeably and shouldn't be. Share of voice is about how much you're being talked about — ad spend, media mentions, social conversation. Share of search is about how much you're being searched for — which is closer to actual purchase intent, because someone typing your name into Google is already past "have I heard of this brand" and into "I'm thinking about this brand specifically." Share of voice can be bought with a bigger ad budget. Share of search is harder to fake — it reflects whether what you're already doing (reviews, word of mouth, local reputation, past advertising) is actually converting into people searching your name. If you want the fuller comparison across all the channels that feed into share of voice for a local business, see share of voice for local businesses. How to calculate your own share of search List your real competitors. Not every business in your category citywide — the specific 3 to 8 businesses a customer would actually be choosing between you and. If you're not sure who those are, start there first; a share-of-search number built on the wrong competitor set tells you nothing useful.Open Google Keyword Planner. You don't need to be running ads to access it — a free Google Ads account gets you in. Use the "Discover new keywords" tool and search each business name individually (yours and each competitor's).Pull 12 full months of data, not a snapshot. A single month will reflect whatever's seasonal in your category — more landscaping searches in spring, more HVAC searches in July and January. A full year averages that out and gives you a number you can actually compare year over year.Add up the monthly search volumes for your name and every competitor's name, then divide your number by the total. That's your share of search.Watch it over time, not just once. A single reading tells you where you stand today. Tracking it quarter over quarter tells you whether you're gaining or losing ground — which is the part that actually matters for decisions. If step 2 through 4 sounds like more manual pulling than you want to do by hand — especially across several competitors, repeated quarterly — our guide to checking brand search volume walks through the Keyword Planner mechanics in more detail, including the gotchas (Keyword Planner shows volume in ranges rather than exact numbers once you're outside an active ad account, and some low-volume local business names return no data at all rather than a true zero — which is a different thing and shouldn't be read as "nobody searches for us"). The limits of this metric Share of search isn't perfect, and it's worth knowing where it breaks down before you lean on it too hard. Businesses with generic names (a "City Dental" in a city with five other dental practices that could plausibly be called that) get noisy data, because Keyword Planner can't always tell which searches meant which business. New businesses with low search volume overall will see share-of-search numbers that swing wildly month to month off small sample sizes. And it only measures branded search — if your category has mostly unbranded search behavior ("dentist near me" rather than "[your business] dentist"), share of search will understate how much of the local market is actually in play, because a lot of that competition is happening in map-pack rankings and reviews rather than name recognition. That's exactly why it's one measurement among four, not the whole picture — see what brand visibility actually is for how it fits with local organic rankings, independent mentions, and AI answers. Checking it without the manual work You can run the calculation above yourself — it costs nothing but time, and the time is mostly in pulling 12 months of data for every competitor and repeating it on a schedule. Tailwind's free Brand Visibility report runs this calculation automatically, alongside the other three signals that make up the full picture — local Google rankings, independent mentions, and AI answers — against the specific competitors you choose.