ESOV Growth Predictor
Out-shout your size and you tend to grow. Enter your share of voice and share of market to get your excess share of voice (ESOV) and a multi-year market-share forecast — built on one of the most reliable laws in media planning.
Share of voice is your slice of category advertising; share of market is your current size. When voice runs ahead of size, the gap — ESOV — predicts growth. The widely-cited rule of thumb is about +0.5 points of market share a year per 10 points of ESOV. This tool turns your numbers into a compounding share path and shows where it settles.
ESOV inputs and forecast
| Year | ESOV (pts) | Predicted growth (pts) | Projected share |
|---|
How to use this predictor
- Enter your share of voice.Your slice of total category advertising over the period — measured by spend or by impressions. If you only track digital, use share of search as a proxy and note it.
- Enter your share of market.Your current market share by sales or revenue. This is your starting size — the thing ESOV is trying to move.
- Set the growth coefficient.The default of 0.5 points per 10 points of ESOV is Binet’s rule of thumb. Nudge it up for distinctive, well-made creative and strong brands; down for weak or generic advertising.
- Choose the horizon.Pick how many years to project. Each year your share rises toward your voice, so ESOV — and the yearly gain — naturally shrinks as you catch up.
- Read the path, then export.You get your ESOV, predicted year-one growth, and a compounding share table. Copy a share link, download the CSV, or print a one-page PDF for the plan.
RGM Expert Says
We reach for ESOV when a client asks the hardest question in marketing: how much is enough? Budgets are usually set by last year plus or minus a bit, or by matching a rival. ESOV reframes it. If you want to grow share, you have to spend a bigger slice of category voice than your current slice of category sales — and the size of that gap sets the pace. It turns “spend more” into a number you can defend to a CFO.
The input people fumble is share of voice itself. They know their own spend but guess at the category total, so the denominator is wrong. Get a real read — from a media audit, a monitoring service, or share of search as a stand-in — before you trust the forecast. The second mistake is treating the coefficient as gospel. Half a point per ten points of ESOV is an average across many brands; strong, distinctive creative beats it, and forgettable advertising can produce almost nothing. That’s why the number is adjustable here.
The most useful thing the model teaches is patience. Watch the yearly gain shrink as your share climbs toward your voice — that’s the equilibrium ESOV drives toward, and it’s why sustained investment beats a one-quarter burst. Brand builds slowly, then compounds. Use this to size the commitment, not to promise a straight line. For the full model, see the brand strategy guide.
How it works
The predictor starts from the definition of excess share of voice, then applies the Binet rule of thumb year by year, letting your share compound toward your voice.
Because your share of market rises each year while your share of voice stays fixed, ESOV shrinks over time — so the model recomputes it every year:
- Share of voice (SOV) — your share of category advertising, held constant across the horizon.
- Share of market (SOM) — your current share; the value that grows.
- Coefficient — share points gained per 10 points of ESOV per year. Default 0.5 (Binet / Jones).
- The path converges: as SOM approaches SOV, ESOV — and growth — approach zero. Sustained voice above size is what keeps share climbing.
The ESOV-to-growth relationship is drawn from Les Binet and Peter Field’s IPA work (Media in Focus, 2017), building on John Philip Jones’ share-of-voice research. The ~0.5-point coefficient and the compounding path are simplifications for education; real elasticity varies by category, starting share, and creative quality. This is illustrative — RGM analysis — not a guarantee.
Share of voice is how you buy share of market
Most budgets are set by inertia. ESOV replaces inertia with a law: to grow, advertise above your size. It is the media-planning expression of How Brands Grow — spending ahead of your share builds mental availability in more category buyers than your current position would predict, and penetration follows. The brands that pull away are usually the ones that held a positive ESOV long enough for memory to compound.
The trap is impatience. Activation shows up this quarter; ESOV pays off over years, and the yearly gain gets smaller as you succeed. Teams see the slowing curve, mistake it for failure, and cut — handing the surplus voice, and the share, to a rival. The point of modeling the whole path is to set the right expectation up front: steady beats spiky, and the equilibrium is where your share meets your voice.
Use it to size the commitment and defend the budget, then pair it with the deeper model on the brand strategy page, where ESOV sits alongside distinctive assets, category entry points, and the 60/40 split.
What good looks like
Read ESOV against your ambition and your category. These are reference points, not rules.
| Situation | ESOV target | What to expect |
|---|---|---|
| Aggressive share grab | +15 to +25 | Fast gains, high spend |
| Steady growth | +5 to +15 | Compounding share |
| Hold position | ~ 0 | Flat share |
| Being out-shouted | Negative | Share erosion |
What the field says
Brands that set share of voice above share of market tend to grow; those that under-invest tend to shrink.
How brands grow: by reaching all the category’s buyers and being easy to think of and easy to buy.
A brand’s share of voice, relative to its share of market, is a leading indicator of where its sales are heading.