Share of voice vs share of market: the rule that steers your brand budget

Share of voice is your share of attention. Share of market is your share of revenue.

The gap between the two predicts whether your market share grows or shrinks.

The verdict: your brand budget shouldn’t be a gut call or a leftover. Set it from the gap between your voice and your market share.

Many B2B companies pick a round number, a percentage of revenue, or whatever’s left after the performance campaigns. None of those tells you whether you invest enough to grow.

Share of voice vs share of market: what’s the difference?

One is an outcome, the other is an investment.

Share of market is where you stand today

Share of market (SOM) is your share of your category’s revenue.

Example: you sell 2 million in a market that turns over 20 million in total. Your share of market is 10%.

It’s a snapshot of what you’ve already sold.

Share of voice is the space you buy or earn

Share of voice (SOV) is your share of your market’s total media presence.

Say all players combined buy or earn 100 units of attention, and you account for 15 of them. Then your share of voice is 15%.

It’s a choice you make today about how much space you take up in your buyers’ minds.

Why the two aren’t meant to match

SOM looks backward at what you’ve sold. SOV looks forward at the attention you’re building now.

So the difference isn’t a measurement error. It’s a control lever.

What is excess share of voice?

Excess share of voice (ESOV) is your share of voice minus your share of market.

Formula: ESOV = share of voice minus share of market

Two examples show how it works:

• 15% voice, 10% market share: a positive ESOV of 5 points
• 8% voice, 10% market share: a negative ESOV of 2 points

Here are the same two cases side by side:

With a positive ESOV, you take up more space than your current size justifies. With a negative one, you’re quieter than your size.

Where the rule comes from

John Philip Jones set it out in “Ad Spending: Maintaining Market Share” in Harvard Business Review (1990).

Les Binet and Peter Field later tested it on the effectiveness cases in the IPA Databank. That’s the work behind their IPA report The Long and the Short of It.

What the rule predicts

Brands with a positive ESOV tend to win market share over time. Brands with a negative ESOV tend to lose it.

Structurally louder than your size? You grow. Structurally quieter? You shrink slowly, while no one notices.

Why leaders are hard to catch

Their market share lets them invest the most in absolute terms. In relative terms, they need to do less to hold their position.

But a challenger that wants to grow must buy more voice than its market share deserves.

That feels uncomfortable: you pay today for growth that only shows up later.

Why is ESOV a budget decision model?

Because you use it to set your budget in advance, not to report after the fact.

Instead of “how much can we spare?”, you ask “how much voice do we need to move where we want?”.

Your ambition sets the ESOV

Three ambitions, three targets:

• Grow market share: you need a positive ESOV
• Defend it: an ESOV around zero is enough
• Accept shrinking, for example retreating to a niche: a negative ESOV is fine

So your budget follows from your ambition, not from whatever happened to be left over.

Flip the calculation around

Work through four steps:

1. Estimate your market share.
2. Pick the ESOV that fits your growth goal.
3. Add the two together: that’s your target share of voice.
4. Estimate what a share that size costs, based on what the market invests in total.

That amount is your starting point, not the figure accounting suggests.

Does this hold in B2B?

Yes, and slightly more strongly. LinkedIn’s B2B Institute ran the analysis with Binet and Field on B2B cases from the same databank.

They found that 10 points of ESOV went with about 0.7% market share growth per year in B2B, against 0.6% in B2C:

So the rule is, if anything, slightly stronger in B2B.

Your voice isn’t only paid media

For a B2B SME, share of voice rarely runs entirely through paid media. It also sits in:

• content and organic visibility
• events
• your people’s visibility on LinkedIn
• earned mentions, now including AI answers

That’s good news. You can build a positive ESOV without a market leader’s media budget.

Tools now measure part of that voice for you. Ahrefs Brand Radar, for example, leads with AI share of voice:

Ahrefs Brand Radar’s product page, October 2026. AI share of voice is the first metric it names.

That’s one slice of your total voice, not the whole picture.

Choosing where your voice comes from is what a well-considered brand strategy underpins: not just what you say, but how much space you take and where.

What are the pitfalls when you do the maths?

ESOV is powerful, but it’s easy to misapply. Three pitfalls to avoid.

1. Treating share of voice as ad spend

If you equate SOV with media spend, you underestimate your own voice.

Organic visibility, PR, content and your team’s presence all count. For B2B brands that live on expertise, earned voice is often the biggest lever.

Our guide to SEO share of voice shows how to measure the organic part.

2. Expecting a direct sale

ESOV buys direction. At roughly 0.7 points of share per year for 10 points of excess voice, it pays off over quarters and years.

It won’t show up in leads this week.

Judge it on short-term numbers and you’ll pull the plug too early. It runs alongside your performance channels, not instead of them.

How to make that longer payback visible is covered in measuring the ROI of branding.

3. Trusting the input too much

Your market share and the total category investment are estimates.

So use round, defensible figures, not false precision.

How do you apply share of voice vs share of market in practice?

Start small and keep it realistic: define the market, map your voice, compare.

Step 1: Define a sharp market

Estimate your market share within a clearly bounded market: a sector, a region, a product type.

The sharper the market, the more usable the figure:

• Too broad: “the entire B2B market” gives you a uselessly small share
• Usable: “accounting software for Flemish firms” gives a figure you can work with

Step 2: Map your voice across all channels

Add up your current voice across every channel combined. Then compare it with your market share.

• Below your market share: you’re giving away ground today
• Above it: you’re investing in growth

That single insight is often enough to lift a budget discussion from gut feel to reasoning.

Step 3: Keep the lead for years

Building that lead isn’t a campaign; it’s a process.

A consistent voice that exceeds your size year after year builds brand equity. That shows up as preference, pricing power and a shorter sales cycle.

Frequently asked questions

Is share of voice the same as share of market?

No. Share of voice is your share of attention in your market. Share of market is your share of its revenue.

What is a good ESOV?

It depends on your goal. To grow, you need a positive ESOV; to defend, around zero is enough.

How fast does a positive ESOV pay off?

Slowly. In B2B, 10 points of ESOV went with about 0.7% market share growth per year.

So how much should you invest in your brand?

Enough to buy more voice than your market share, if growth is the goal.

That’s the real outcome of a positive ESOV: not louder for its own sake, but bigger, because you buy today the space you fill tomorrow.

As a branding agency, we help B2B companies in the Benelux sharpen their share of voice and steer budget toward growth.

Want a first read on your own gap? Get in touch and we’ll estimate your voice against your market share with you.