What Does It Cost You to Grow? Do the Math

TL;DR 

Growth is a mathematical output of a system, and most traditional B2B companies are running that system without the numbers underneath it. 

Three components make up the unit economics layer of your revenue factory: 

• Cost of growth tells you whether your revenue factory funds its own growth or works against it. Customer acquisition cost, payback period, and the 3:1 lifetime value benchmark are all part of this calculation. 
• Cost of retention is almost always invisible in traditional B2B, and a very low number usually means account management is under-resourced. 
• Expansion or contraction tells you whether your existing accounts are growing or shrinking, once you have tiered your book of business to see which accounts produce the revenue. 

Work through all three, and you stop having a sales problem you cannot explain. You start having a math problem, and math problems can be solved. 

Why Growth Targets Keep Surprising You 

There is one question I ask every B2B leader I sit down with, and I have asked it hundreds of times by now.  

What does it cost you to grow? 

I mean the full, honest, all-in number. What it costs for your business to bring on one net new customer and keep them long enough to make money. Most leaders start explaining their marketing spend, or the commissions and splits paid out when a new customer gets landed, but both of those are only part of the total. 

Almost nobody can answer it, because almost nobody has calculated their true cost of growth.  

The system is already running, with salespeople, marketing, customers, and revenue coming in, but the math underneath it was never calculated. Without that math, you cannot price growth, you cannot resource it, and you cannot build on it with any confidence. You are running a revenue system you do not truly understand, and you are wondering why the results keep surprising you. 

The companies we work with at Roadmap are manufacturers, distributors, dealers, and professional service firms, typically in the $5 million to $55 million revenue range. When they miss growth targets, the cause is rarely a weak product or a weak team. They are getting what they get because they are running a system without the mathematical models and targets needed to drive it forward. 

They have never calculated their cost of retention. They have never looked at their book of business account by account and asked which ones are producing, which ones are declining, and which ones have gone silent while costing more to serve than they return. 

So they rely on hope. They set targets based on last year’s number plus a percentage. They call it a plan. I call it a hopecast. 

There is a better way to set the number, and it comes down to three components you can calculate, track, and act on: 

1. Cost of growth tells you what it costs to bring on new business. 
2. Cost of retention tells you what it costs to hold onto the business you already have. 
3. Your expansion or contraction ratio tells you whether your existing accounts are growing or shrinking. 

Together they form the unit economics layer of your revenue factory. 

What Is Your Cost of Growth? 

Cost of growth is a ratio. It is the top-level number that tells you whether your growth is healthy and whether you have a revenue factory that will fund growth or one that is putting you in a hole. 

Here's how to calculate it: 

1. Total your acquisition costs, counting every expense that goes toward winning new business. 
2. Divide that total by the gross margin or free cash flow generated from your sales. 
3. Multiply the result by 100 to express it as a percentage. 

Everything that goes toward winning new business belongs in your acquisition cost total: 

• Sales team salaries and commissions both count, since they are the direct cost of winning business. 
• Marketing spend belongs in the total, across campaigns, content, and advertising. 
• Trade show costs count, including travel and booth expenses. 
• Software costs count, and your CRM sits at the top of that list. 
• Association memberships count, because they exist to put you in front of buyers. 

How it works: 

Say you brought in $1 million in new revenue from ten new customers last year. The free cash flow from those customers is $500,000, and it cost you $250,000 to win them. Your cost of growth is 50 percent. You are spending fifty cents to earn every dollar of free cash flow. 

The closer that number runs to 100 percent, the closer your free cash flow runs to break even. From there, the result tells you two things: 

• Under 100 percent, your revenue factory funds its own growth. 
• Over 100 percent, growth is potentially cannibalizing the business depending on lifetime value. 

The threshold depends on how the business is built. 

A company with strong reoccurring revenue can be at close to 100 percent and still be in good shape, because that customer keeps buying after you have already paid to win them. 

For most traditional B2B companies, the acquisition ratio is the first ratio to determine, because it tells you whether the structure is solid before you spend another dollar trying to grow. 

The ratio also shows you whether one spending decision worked. Say you paid for an expensive billboard last year, and it brought in no new customers. That spend pushed your cost of growth up and got you nothing in return. So don't do that again, and your cost of growth rightsizes. 

How to Calculate Your Customer Acquisition Cost 

You already have everything you need for this one. Take the total acquisition costs you added up for the first ratio and divide them by the number of new customers you landed in that period. 

Using the same numbers, $250,000 in acquisition costs across ten new customers puts your customer acquisition cost at $25,000. 

Now you have two numbers that work together: a 50 percent cost of growth and a $25,000 customer acquisition cost.  

Together they form the foundation to make a decision about whether to invest more or less in acquisition to bring in additional customers. 

Payback Period and the 3:1 Benchmark 

Two more numbers finish the acquisition picture. 

The first is your customer acquisition cost payback period. In a typical traditional B2B company, a customer lands and then buys again every month or every quarter or is cyclical with seasons, so the question is how many months of that repeat business it takes to pay back what you spent acquiring them. The answer might be four months, eight, or sixteen. It changes how you think about resourcing onboarding and retention, because a long payback period puts far more weight on holding onto the customer. 

The second is your lifetime value to customer acquisition cost ratio. Higher is better here, and a good rule of thumb is that anything over 3 to 1 puts you in generally healthy territory. Below 3 to 1, your growth model is likely unsustainable, and the cause is usually one of three things: 

• Churn is running too high, and customers leave before they pay you back. 
• Acquisition is costing too much for the free cash flow each customer returns. 
• Your average account size and average transaction size are too small to carry the model. 

You now have four numbers describing the acquisition side of the business: 

1. Cost of growth ratio shows you whether the structure is sound. 
2. Customer acquisition cost gives you the price of one net new customer. 
3. Payback period tells you how long it takes to earn that money back. 
4. Lifetime value to acquisition cost ratio confirms whether the model sustains itself. 

Take all four together, and you can tell whether your acquisition side is working, and which of the four numbers is causing the problem if it isn't. 

What Does It Cost You to Keep a Customer? 

Cost of retention runs in parallel with cost of growth, and in traditional B2B companies it is almost always invisible. 

Cost of retention is calculated the same way as cost of growth. 

Your cost of growth is twenty cents on every free cash flow dollar to win new business. Cost of retention is the same measure applied to your existing book of business: how many cents on every free cash flow dollar it costs to keep it. 

You already have the numbers from the acquisition calculation, so use them again here. When you tallied acquisition costs, you counted the business development salary, the CRM, the marketing, and the trade shows. But you see existing clients at those trade shows too, so not all of that cost belongs to acquisition. Generally, some of each cost goes to acquisition, and some goes to retention. 

Do the same across everything that goes into keeping accounts. Account management wages, software, and events all belong, and so do the volume discounts you extend to keep the business. The result is a cost of retention expressed as a percentage of free cash flow. 

Retention almost always costs less than acquisition. A business with a 30 percent cost of growth will often show an 8 percent cost of retention. Single digits or low double digits is what we see across most traditional B2B companies. 

The same work gives you a few more retention numbers: 

• You get a dollar figure per account, which might tell you that you spend $1,500 a year retaining a customer. 
• You get a lifetime retention cost ratio measured against that account. 
• You get a retention payback period. 

Those numbers give you what you need to make resourcing decisions for this side of the business, decisions most companies never think to make because they never had the numbers in front of them. 

A retention cost that lands very low deserves a second look. It often signals that account management is under-resourced, and that expansion revenue is sitting there unclaimed. 

Tiering Your Book of Business 

The third component moves from cost to concentration. Before you can tell whether your book of business is expanding or contracting, you have to know what is in it. 

Break your accounts into three tiers, or four depending on the nature of your business: 

• Tier one accounts are your strategic accounts, carrying the highest revenue, the deepest relationships, and the largest potential future value. 
• Tier two accounts are your growth accounts, solid and reliable, and some of them will become tier ones with the right attention. 
• Tier three accounts are passive or transactional, ordering occasionally with shallow relationship depth and little likelihood of becoming more than one-off orders. 

Then look at how the revenue distributes across those tiers. In nearly every book of business I have tiered, and I have run this exercise with many groups, roughly 80 percent of revenue comes from tier one and tier two accounts, and those accounts represent about 20 percent of the customers. The split might land at 78 and 22, but it lands in the same place with striking consistency. 

What surprises leaders more is how few accounts fall into those top tiers once you look at fit and revenue together. A business doing $15 million or $20 million a year can find that roughly 20 accounts produce 80 percent of the revenue. Those are the accounts that are most important to the business. If that business wants to grow, the path is to keep those 20 accounts and add five more tier one or tier two accounts alongside them. 

Is Your Book of Business Expanding or Contracting? 

Once the accounts are tiered, the next question you need to answer is whether that book of business is growing or shrinking. 

Churn on your tier one and tier two accounts is where to start. If 20 accounts carry 80 percent of your revenue and you run a 10 percent churn rate, you are going to lose two of them and 10 percent of that revenue along with them. 

Now bring expansion into the calculation. If that same book of business expands by 15 percent a year while you lose 10 percent to churn, it grows by roughly 5 percent on its own. Run your churn rate and your expansion rate together, and you have a between-the-goalposts forecast of where your book of business is heading before the year ends. 

The math points directly at two moves: 

1. Retain those customers. Every customer you keep is revenue you don't have to replace. 
2. Resource your account management. Putting more effort into account management raises your expansion rate. 

Do both, and you get the benefit twice over. 

The same math works in reverse when a book of business is contracting. A book of business going backwards is often a sign of under-resourced retention, meaning not enough account management is in place. Resourcing it properly can take that book of business from negative 20 percent to flat, a 20 point swing, just by stopping the bleeding. Either direction, the numbers show you where to fix the problem or where to take the opportunity in front of you. 

Turning a Sales Problem Into a Math Problem 

Put the three components together, and you have the true unit economics of your business as a revenue system: what it costs to grow, what it costs to retain, and whether your book of business is concentrated in the right accounts and moving in the right direction. 

Nearly every client I meet is surprised by at least one of these numbers the first time we calculate them together: 

• Cost of growth usually runs higher than expected. 
• Retention cost stays invisible until it is measured, and it lands lower than anyone predicts. 
• The group of accounts carrying 80 percent of the revenue turns out to be far smaller than leaders assume. 

Surprise is useful. Surprise means you now know something you did not know before, something you can act on and engineer around. You cannot fix what you have not uncovered, and you cannot uncover what you have never measured. 

Work through all three components, and you stop having a sales problem where targets get missed for reasons nobody can name. You start having a math problem instead. A sales problem runs on hope, effort, and luck. Math problems can be solved, and that is the difference between hopecasting and forecasting. 

Run the math. Most of your competitors never will. 

Part two of this series picks up from the signals these three numbers give you. Once you know whether things are healthy or whether something structural needs adjusting, the next question is what to do about it, including how the efficiency math changes across different go-to-market motions. 

We Built the Model for You. Use It. 

The three components covered here are built into Roadmap's Revenue Factory Toolkit. The formulas are done, so put your numbers in and see where you stand: Revenue Factory Toolkit 

Benchmark Your Metrics Against Your Peers 

The Go-To-Market Readiness Index scores you on the Metrics and Forecasting side of your business, and it asks the same questions this article does. Have you calculated your acquisition and retention efficiency ratios? Do you model your CAC payback period? Do you tier your accounts and track churn and expansion revenue? You will see how you score against your peers, and you get a one-on-one review of the results. It is free, and it takes very little time.