Protect Your Exit with the sustainable rate of growth formula

Trevor Stevenson-Platt

25 Jan 2026 — 4 min read

You can grow your way into a lower valuation. I’ve watched great owners sprint past a quiet line buyers use to judge you, then get punished at the table. The simple guardrail that could have saved them: the sustainable rate of growth.

That number tells you the fastest you can grow using your own profits, no fresh equity, no papering over cracks with heroic payment terms. Buyers care because it screams discipline. It tells them if your growth is real or rented.

Here’s the uncomfortable truth. If your growth runs above that line, your exit gets more fragile by the week. Sit below it for too long and you hand easy upside to the buyer, for free.

What the formula really says

Your long-run speed is limited by how much profit you keep and how effectively you turn equity into profit.

Growth = Return on Equity × Retention Ratio

Return on equity: net income ÷ average equity. How hard each pound of equity is working.
Retention ratio: the share of profit you keep after owner distributions. Earn £1,000,000, distribute £200,000, retain 80%.

Multiply them. If ROE is 20% and you retain 80% of profits, your sustainable growth is 16%. That’s the speed you can hold without fresh equity, without piling on risky debt, without starving the business.

Messy real life? Adjust it. Treat tax-adjusted owner distributions as dividends. Use average equity for the period. You’re not chasing decimal-point precision; you’re drawing a clear boundary you can defend in a sale.

A quick way to compute yours today

You don’t need a finance team, just last year’s numbers and common sense.

Net income after tax
Total owner distributions, including any extras that act like dividends
Beginning and ending equity to get an average

Now do the math:

ROE = net income ÷ average equity
Retention = 1 − (distributions ÷ net income)
Sustainable growth = ROE × retention

Example: Average equity = £5,000,000. Net income = £1,000,000. Distributions = £200,000.

ROE = 20%
Retention = 80%
Sustainable growth = 16%

What does that tell you? If you try to grow revenue 30% without outside cash, you’ll stretch suppliers, underinvest in talent, and drain working capital. A buyer will see it and lower your price, ask for a bigger working capital peg, or both.

Why this matters when you sell

Buyers don’t just price your past. They price the path you’re on. Your sustainable growth rate shows whether your growth is funded from within or burned into payables and panic.

Push above your sustainable line and three things happen:

Working capital balloons because you ship faster than cash comes in.
You grab debt you didn’t plan for, often at ugly terms.
Maintenance slips, which shows up in churn, quality drift, and staff turnover.

Sit below your line for too long and you gift the buyer an obvious, internally funded upside. They’ll model it as theirs, not yours, and they won’t pay you for it.

Timing matters. Twelve months of disciplined growth inside your sustainable band tells a story buyers trust. It says you understand your engine, know where the edges are, and respect cash.

How to lift your sustainable growth before you exit

You have two levers: make equity earn more, or keep more of what you earn. Work both lightly and quickly, and your exit gets sturdier.

Raise return on equity (margin, efficiency, capital mix):

Lift prices where value is clear; prune low-margin lines; bundle to raise average order value
Shorten the cash conversion cycle: collect faster, move slow inventory, improve vendor terms without bruising relationships
Sell idle or non-core assets that drag returns; put them to work or let them go
Use sensible debt for long-lived assets so equity isn’t doing all the heavy lifting

Increase retention (reduce avoidable cash leakage):

Pause non-essential distributions in the final year before a sale
Redirect pet projects that don’t move revenue or reduce risk
Channel savings into sales capacity, customer success, and systems that scale without drama

Keep it clean. Avoid raising fresh equity right before a sale. Avoid spiky growth you can’t defend with internal cash. Buyers punish last-minute acrobatics and reward stable, internally funded growth.

Put the number to work in your deal prep

Operate just under your sustainable rate for at least two quarters, ideally four.

That:

Builds a working-capital story you can prove with monthly data
Gives you cover to say no to reckless pushes that feel good now but hurt valuation
Lets you talk to buyers like a peer, with a clear why behind your growth choices

Build a simple working-capital bridge alongside it. Show how each point of growth converts into cash needs. When a buyer asks why you held growth at 16% instead of chasing 30%, show the math, not the mood. Confidence is contagious when it’s backed by numbers that the other side already respects.

If your number is lower than you like, pull the fastest levers: price discipline in key segments, better collections, tighter purchasing, and trimming low-yield experiments. Those moves shift ROE and retention faster than big strategic overhauls. Prove the change with trend lines, not promises.

Key takeaway

Grow at a pace your own profits can fund, then sell. The market pays a premium for growth that’s real, repeatable, and internally financed, and discounts growth that exists because you outran your cash.