Growth is no longer the whole story

For most of the last decade, a growth-stage software company could raise its next round on one number — revenue growth. If ARR was climbing fast enough, the rest was forgiven. Burn was treated as the price of ambition, and the market rewarded the companies that spent the most to grow the quickest.

That era has closed. Capital costs more than it did, buyers take longer to decide, and both lenders and equity investors have moved their attention from how fast a company grows to how efficiently it grows. The question underneath every financing conversation in 2026 is the same. Does this growth stop the moment funding does, or does the business model drive it sustainably?

Capital efficiency is how you answer that question with numbers rather than adjectives. Below are the five metrics we reach for first when we look at a business, why each one matters, and what a healthy reading looks like.

Net new ARR per euro of burn

Start with the plainest version of the question. For every euro the company burns, how much new recurring revenue does it buy?

Two businesses can both grow 30 percent in a year and look identical on a chart. One adds a euro of new ARR for every 50 cents of net burn. The other spends three euros to add the same euro of ARR. On the growth line they are twins. As businesses they are nothing alike. The first is converting capital into durable revenue at a profit to itself. The second is renting growth and will stop the day the tap closes.

This single ratio tells you whether more capital will compound or simply disappear. It is the first thing we reverse-engineer from a company’s numbers, because it cuts through the narrative faster than any deck.

The burn multiple

The burn multiple, popularised by David Sacks, is the formal version of the same idea. It divides net burn by net new ARR over a period. A lower number is better, because it means less cash consumed per unit of recurring revenue created.

The scale Sacks proposed is a useful shorthand. Below 1 is exceptional. Between 1 and 1.5 is very strong. Between 1.5 and 2 is respectable for a company still investing hard in growth. Between 2 and 3 deserves scrutiny. Above 3 is a warning that the business is buying growth it cannot yet afford. Early-stage companies naturally sit higher on this scale, and mature ones trend toward zero as they approach self-funding. What matters is the direction of travel. A burn multiple falling quarter on quarter is often a better signal than an already-low number that is drifting up.

The Rule of 40, read properly

The Rule of 40 is the best-known efficiency test in software. Add your growth rate to your profit margin, and the result should clear 40. It remains a good filter. The trouble is that most people stop at the headline number.

In 2026 the composition of the 40 matters more than the 40 itself. A company that clears the bar through 60 percent growth and heavy losses is a very different risk from one that clears it through 25 percent growth and real margins. Both pass. Only one is durable when capital gets expensive.

The median public software company has spent much of the past two years below 40, and AI infrastructure costs are quietly pulling reported margins down even at companies where the underlying business is strong. When we read a Rule of 40 score, we always ask how it was earned. Growth paired with improving unit economics is the profile that compounds. A 40 built entirely on burn is borrowed time.

The magic number

The decisive metric moves from the whole company to the growth engine specifically. The magic number measures how much new ARR each euro of sales and marketing spend produces, usually by comparing net new ARR in a quarter to the prior quarter’s sales and marketing cost.

A reading around 0.75 or higher generally means the go-to-market motion is efficient enough to justify spending more into it. Below roughly 0.5 suggests the engine is straining, and pouring in more capital will mostly widen losses rather than accelerate revenue. The magic number tells a founder whether the honest move is to step on the accelerator or fix the engine first.

Customer acquisition payback

One more number belongs in the set, because it connects the others to cash. The CAC payback period measures how many months of gross margin it takes to recover the cost of winning a customer. A payback inside twelve months is generally healthy for a business selling to other businesses, and the best companies recover their acquisition cost faster still. A payback stretching well beyond eighteen months is a signal that either the cost of winning customers is too high or the early revenue from them is too thin.

Payback matters because it governs how quickly capital recycles. When a customer pays back the cost of acquiring them in nine months, the same euro of capital can be put to work again within a single year. When payback takes two years, capital is tied up far longer, and the business needs more of it to grow at the same rate. Two companies with identical growth can have completely different capital needs purely because of how fast their acquisition spend comes back.

How to move these numbers

None of these metrics are fixed. The burn multiple improves when a company either grows more efficiently or trims spend that is not producing revenue. The magic number improves when go-to-market becomes more targeted, so that sales and marketing euros land on customers who convert and stay. Payback shortens when pricing is right and onboarding turns new customers into paying, retained ones quickly. Retention, which sits underneath all of it, improves when the product does more of the work of keeping customers than the sales team does.

The point is not to chase a perfect score on any single measure. It is to show a clear direction of travel. A financier reading these numbers is looking less for a flawless snapshot than for evidence that the business understands its own economics and is steering them the right way.

Why this matters for how you fund the business

These five metrics decide more than valuation. They decide which kinds of capital are even available to you, and on what terms.

A capital-efficient business has options that an inefficient one does not. Because its growth pays for itself, it does not need to sell a large share of its equity to fund the next stage. It can service revenue-linked repayments comfortably, because the same efficiency that impresses investors also generates the cash flow that non-dilutive capital is repaid from. The companies with the strongest efficiency metrics are precisely the ones that should think hardest before raising equity, because they have the least need to give ownership away.

Inefficient growth narrows the menu. Equity becomes the only realistic option, and it comes at the moment of weakest leverage. That is the quiet cost of ignoring these numbers until a raise forces you to confront them.

At Round2 Capital, efficiency is not a preference. It is the thing we underwrite. Our starting point is growth capital for recurring-revenue software businesses without taking equity, and a company that already turns capital into durable ARR is exactly the profile the model is built for. If your metrics are heading in the right direction, you have more ways to fund your growth than you may think.