Share of Voice (SOV): Why It Matters More Than Ever for Brands

What is Share of Voice?

Share of Voice (SOV) is a simple but powerful concept. It measures how much visibility your brand has in a market compared to your competitors. Think of it as the “loudness” of your brand voice in a crowded room.

There are different ways to define SOV, depending on the channel:

1. Advertising SOV – The percentage of total advertising spend or impressions in your category that comes from your brand. (e.g. if you spend 20% of all category ad spend, your SOV is 20%.)

2. PR SOV – The proportion of media coverage or press mentions your brand receives compared to competitors.

3. Social SOV – The share of online engagement, conversations, or mentions your brand has in comparison to others.

In this article, we’ll focus on advertising SOV, because it’s the one brands control most directly. You can spend more, increase your visibility, and influence your share of voice. But advertising costs money - a lot of it - so brands want to be sure they’re investing at the right level.

Why is SOV Important? The ESOV rule

What Is ESOV?

Excess Share of Voice (ESOV) is one of the most widely recognised principles in marketing effectiveness, built on the simple relationship between a brand’s share of voice (SOV) and its share of market (SOM). SOV reflects the proportion of total advertising spend or impressions a brand commands within its category, while SOM measures the brand’s actual market share. ESOV is the difference between the two (SOV – SOM), and in straightforward terms, it shows whether your brand is “shouting louder” or “quieter” than the size of your market position.

Why does your ESOV matter?

Decades of research have consistently shown that ESOV is a reliable predictor of growth. Peter Field and Les Binet, in their landmark IPA studies, found that for every 10-point ESOV, brands gained around 0.5% of market share per year: when SOV falls below SOM, brands decline, but when SOV is sustained above SOM, brands grow over the long term.

These findings have been replicated by both Nielsen and the LinkedIn B2B Institute, the latter showing that the ESOV principle remains true in B2B contexts too

The reason ESOV works is simple: advertising builds mental availability, reinforces brand salience, and ensures your brand occupies space in consumers’ minds. Outspend your market share and you grow; underspend and your competitors take that space instead.

SOV as a Tool for CMOs

In today’s advertising landscape, CMOs are under constant pressure to do more with less. Boards and executive teams often set ambitious growth targets, but the budgets allocated to marketing are not always sufficient to achieve them. This disconnect can leave marketing leaders in an impossible position: expected to deliver outcomes that the available resources simply cannot support.

Simply asking for extra budget is rarely effective, especially without compelling evidence. Demonstrating ROI and campaign effectiveness is, of course, critical — but it may not be enough to win over a board that views marketing spend as a cost rather than an investment. This is where the Excess Share of Voice (ESOV) framework becomes an invaluable tool.

If analysis shows that your brand is under-investing relative to market share, this becomes a powerful argument for increased budget. Rather than cutting back, the board can see that protecting and growing the brand requires higher spend. Even if additional funds are not secured immediately, framing budget discussions around SOV and ESOV helps set realistic expectations and positions marketing as a strategic growth driver, not just a cost centre.

The problems in measuring SOV in today’s market

While understanding your brand’s Share of Voice (SOV) has never been more critical, obtaining accurate data has become increasingly complex. Not so long ago, the task was relatively straightforward. Television dominated advertising spend, audience ratings were published openly, and both brands and agencies could easily calculate their exact share of voice within a given category. With one dominant medium and transparent reporting, marketers had a clear picture of how loud their brand was compared to competitors.

Today, the situation is dramatically different. Television now represents less than half of total advertising spend, while digital platforms such as YouTube, TikTok, Facebook, and Instagram capture an ever-growing share of investment. The challenge is that these platforms operate as “walled gardens”: they provide data about your own campaigns but rarely reveal information about competitor activity or the broader landscape. As a result, marketers are left with blind spots.

Consider a brand that spends heavily on YouTube and sees strong internal reporting on impressions and reach. Without knowing how much competitors are also investing on the platform, that brand may assume it is cutting through the noise. In reality, it might represent only a small fraction of the total ad volume in its category, meaning its message is being drowned out. Alternatively, the opposite could be true: the brand might actually hold a dominant position but, unaware of this, underutilises the data to push for more budget or defend its spend.

This fragmentation means most brands no longer know their true SOV - neither at the individual platform level nor across their entire media mix. Without this visibility, it becomes far harder to plan effectively, allocate budgets wisely, or understand whether your brand is over- or under-investing relative to the market. And here lies the bigger issue: if you don’t know your SOV, you can’t calculate your Excess Share of Voice (ESOV). Without that link, brands lose one of the most reliable predictors of long-term growth. In effect, they are forced to make some of their most important strategic decisions in the dark, risking both wasted spend and missed opportunities to grow market share.

The Risks of Not Knowing Your SOV

The greatest danger, however, comes from not knowing your true SOV at all. Research by Thomas Whipple, from Cleveland state University, demonstrated that when managers operate without reliable SOV data, they make flawed budget decisions: some overestimate their presence and cut back too soon, while others underestimate it and throw money at the wrong channels. In both cases, strategies end up built on assumptions rather than facts, creating inefficiency at best and decline at worst.

So What Can Brands Do?

This is where single-source data becomes a game-changer. Instead of piecing together incomplete reports from TV and self-serving dashboards from digital platforms, single-source measurement follows the same panel of people across both traditional and digital media—including the walled gardens such as YouTube, TikTok, and Meta. This approach provides a clear, like-for-like view of advertising exposure, enabling brands to see their true SOV on each platform as well as their total SOV across all major channels. With this clarity, CMOs can make smarter investment decisions, balancing budgets between platforms rather than overspending in one area and starving another. It also equips marketing leaders with the evidence they need to defend or request larger budgets at board level, showing not just campaign ROI but the competitive risks of underinvestment. In short, knowing your real SOV is no longer optional - it is essential for protecting today’s performance, planning future growth, and making sure every pound of spend counts.

The SOV Hack: Dive Even Deeper

But what happens if you simply don’t have the budget to cut through the noise? Should you stop advertising altogether? The answer is no, because some advertising is always better than none, provided it’s done in a smart, strategic way. In fact, when budgets are tight, strategic thinking becomes even more critical, and having the right data is the difference between wasted spend and efficient growth.

One smart approach is to identify channels where your competitors are underspending and redirect your efforts there. By focusing investment in these less crowded spaces, you can achieve a disproportionately high share of voice without matching the bigger players pound for pound.

There’s another, even more powerful tactic: using data at a granular level to understand who your competitors are targeting. When you combine demographic targeting insights with SOV data, you uncover opportunities that others are missing.

For instance, if rivals are investing heavily in reaching women aged 25–34 on Facebook, you might decide to shift your spend to men aged 45–54 on Instagram, where fewer brands compete. The result is that you achieve a much higher share of voice in that audience, even with modest spend. This approach doesn’t just stretch your budget further—it ensures your advertising is visible, memorable, and efficient. In other words, you’re not just shouting into the void; you’re being heard where it matters most.

Conclusion

In a world where advertising budgets are under constant scrutiny, understanding and managing Share of Voice (SOV) has never been more important. Decades of research, from Field and Binet to Nielsen, show that brands that invest above their market share—what’s known as Excess Share of Voice (ESOV)—are the ones that grow, while those that underspend slowly shrink. Yet in today’s fragmented media landscape, with TV no longer dominant and digital platforms like YouTube, TikTok, and Meta operating as walled gardens, most brands don’t know their true SOV. This lack of visibility creates strategic blind spots, leading to wasted spend or missed opportunities. The solution lies in single-source data, which reveals a brand’s true SOV across both TV and digital, helping CMOs allocate budgets smartly, justify investment to the board, and protect long-term growth. And even for brands with limited resources, smart use of SOV data—by identifying underinvested channels or underserved demographics—can deliver outsized impact. In short, SOV isn’t just a metric; it’s a compass for growth, and knowing it is essential for every brand that wants to stay ahead.