Share of voice (SOV) is a brand's share of the category's advertising spend or attention. Share of market (SOM) is its share of category sales. Excess share of voice (ESOV) is the gap: SOV minus SOM. A positive gap means you are talking louder than your size, and research links that to share growth. It is a signal, not a guarantee.
Key takeaways
- SOV measures how much of the conversation or spend you hold; SOM measures how much of the sales you hold.
- ESOV equals SOV minus SOM, in percentage points.
- Binet and Field's research is the usual source for the link between ESOV and share growth; the link is an average, not a rule for every brand.
- Define what "voice" means before you compare: ad spend, social posts, mentions and search visibility give different answers.
- Read ESOV alongside creative quality and category conditions, not alone.
What is share of voice?
Share of voice is your brand's portion of the total activity in a category. It is calculated as your metric divided by the total for all compared brands, times 100.
The metric can be media spend, number of ads, social posts, mentions or search visibility. Brand24's explainer describes SOV as forward-looking, because it shows the attention a brand is buying now. The choice of metric matters: spend share and mention share can tell different stories about the same category.
What is share of market?
Share of market is your sales divided by total category sales, times 100. It is backward-looking: it records what customers already bought.
Choose the category boundary with care. A brand with 10% of a narrow category and 2% of a broad one has two different SOMs, and the ESOV changes with it.
What is excess share of voice?
ESOV is the difference between the two: SOV minus SOM. Positive means you are over-investing in voice relative to your size; negative means you are under-investing.
A hypothetical example, using made-up numbers:
| Brand | Share of market | Share of voice | ESOV | Reading |
|---|---|---|---|---|
| Brand A | 10% | 15% | +5 points | Louder than its size |
| Brand B | 10% | 8% | -2 points | Quieter than its size |
| Brand C | 30% | 30% | 0 | In balance |
The pattern follows the example on Brand24's page, which gives +5 points for 15% SOV against 10% SOM, and -2 for 8% against 10%. Brand C is added here for illustration.
Where does the ESOV idea come from?
The link between SOV, SOM and growth goes back many decades; one practitioner article says marketers have used the rule for over half a century. The modern evidence is credited to Les Binet and Peter Field, whose work for the Institute of Practitioners in Advertising (IPA) in the UK analysed effective campaigns. DPRandCo's summary names Binet and Field, and the Ehrenberg-Bass Institute, as having found that ESOV correlates with market share growth. Brand24 credits Binet and Field with a 2013 analysis of 171 campaigns.
The IPA's own article by Robert Brittain on capturing an extra share of the recovery defines ESOV as investing a greater share of category media spend than the brand's market share. It says that doing so is the foremost way to increase market share, and that high-ESOV campaigns were more often linked to long-term gains.
How much growth does ESOV buy?
On average, a modest amount, and sources differ. Brand24 says every 10 points of positive ESOV is associated with roughly 0.5 points of annual share growth. DPRandCo quotes 0.7 points a year for B2C and 0.6 for B2B. Treat these as directional.
Brand24 also notes that Binet and Field's later work shows the same gap does not give the same growth for every brand, because size, category and conditions matter. Check the original studies before you build a plan on any figure.
How do you use SOV and ESOV in practice?
- Pick the competitive set and the category. Use the brands a buyer would compare, and a category definition you can defend.
- Choose the voice metric. Paid spend is closest to the research. For social, count posts and ads; for search, visibility.
- Compute SOV and SOM over the same period.
- Subtract to get ESOV, and track it quarterly.
- Look at the mix. Which markets, formats and messages make up your voice? Our post on share of voice by market shows why a pooled figure misleads.
- Check the content. Voice that repeats what rivals say buys less than voice that is distinct; see marketing whitespace.
SOMIN's Strategy product maps competitor content by market so that the SOV side can be measured from real posts and ads, with the underlying content behind each figure.
What are the limits of ESOV?
- Spend is not attention. A larger budget with weak creative may earn less than a smaller, sharper one.
- Metric mismatch. Brand24 notes that most ESOV studies measured advertising or media spend, so the findings do not automatically apply to social mentions, search or AI visibility.
- Data gaps. Few brands see rivals' real spend. Estimates carry error.
- Category noise. Pricing, distribution and launches move share regardless of voice.
FAQ
What is a good ESOV?
Positive is the aim. Beyond that, no single number fits every brand. The research sources quote averages, but the right level depends on your size, category and budget.
Can ESOV be negative?
Yes. It means your brand holds a smaller share of category voice than of category sales. The research linked to this idea suggests such brands tend to lose share over time, on average.
Is share of voice only about advertising spend?
No. It can be built from spend, ads, posts, mentions or search. State which one you used, because the results are not interchangeable.
Does ESOV work for B2B?
One source cited above reports a B2B effect, slightly smaller than B2C. It refers to research by the LinkedIn B2B Institute and by Binet and Field. Check those studies for your sector.
How often should I measure it?
Quarterly is enough for most brands, with a yearly review of the category definition.
