The fundraising math nobody does out loud decides whether your next round was worth taking. If you raise two million at a ten million post-money valuation, you sell twenty percent of your company. That twenty percent needs to buy you enough growth to justify the dilution. Do the math before you sign. Run the dilution math before you sign, while the answer can still change the terms.
CAC payback period tells you if your growth is sustainable
Customer acquisition cost payback period is the number of months it takes for a customer's revenue to cover the cost of acquiring them. If your CAC payback is under twelve months, your growth is sustainable. If it is over eighteen months, you are spending too much to grow and will run out of cash before the customers pay back their cost.
The mistake is measuring CAC in aggregate. Break it down by channel. Your CAC from referrals might be three months while your CAC from paid ads is twenty-four months. Knowing this changes where you spend. Cut the channels with payback over eighteen months. Double down on channels under twelve. The aggregate number hides the insight.
Burn rate is a strategy as much as a number
Your burn rate should be a deliberate choice, not an accident. High burn is a bet that you will grow fast enough to raise your next round before you run out of money. Low burn is a bet that you can reach profitability or extend runway indefinitely. Neither is right or wrong. What is wrong is not knowing which bet you are making.
The burn multiple is the metric that matters: net burn divided by net new revenue. A burn multiple of one means you are spending one dollar to generate one dollar of new revenue. Below one is excellent. Above two is concerning. Above three means your growth is too expensive to sustain. Calculate it monthly and trend it over time.
Revenue recognition is simpler than you think
For early-stage B2B SaaS, revenue recognition is straightforward: recognize revenue ratably over the contract period. A twelve-month contract for twelve thousand dollars is one thousand dollars per month, recognized monthly. Annual prepayments are a liability until you deliver the service.
The mistake is booking the full contract value as revenue in month one. It inflates your numbers, misleads your investors, and creates a restatement nightmare later. Use a simple revenue recognition schedule from day one. Your future self, your investors, and your accountant will thank you.
Your financial model should fit on one page
The one-page financial model has four sections: revenue, cost of goods sold, operating expenses, and cash. Revenue is customers times average contract value. COGS is hosting plus support costs. OpEx is salaries plus tools plus marketing. Cash is beginning balance plus revenue minus expenses.
Update it monthly with actuals. Compare actuals to projections. When actuals diverge from projections by more than twenty percent, update the model. The model is not a prediction. It is a planning tool that helps you make decisions about hiring, spending, and fundraising. A model that is six months out of date is worse than no model because it creates false confidence.
Pricing is the most powerful financial decision
A ten percent price increase has more impact on your bottom line than a ten percent increase in customers or a ten percent decrease in costs. Yet most founders spend more time on customer acquisition and cost cutting than on pricing optimization.
Review your pricing every six months. The signals that you should raise prices: win rate above forty percent, customers not negotiating, churn below five percent, and competitors priced higher. The signals that you should not: win rate below fifteen percent, heavy negotiation on every deal, and churn above ten percent. Raise prices for new customers first. Grandfather existing customers for twelve months, then migrate them.
Frequently asked questions
How does startup dilution math work?
Raise two million at a ten million post-money valuation and you have sold twenty percent of the company. Every round follows the same division. The question is whether the capital buys growth worth more than the slice.
How much should I sell in a round?
Fifteen to twenty-five percent is the normal band. Above thirty and the next rounds get structurally hard; below ten and you probably raised too little to change the trajectory.
How much should I raise?
Enough to reach the milestone that prices the next round, plus a third as buffer, because plans slip. Eighteen months of runway is the standard answer; twelve is the floor that still lets you build.
Is a higher valuation always better?
No. A price you cannot grow into turns the next round into a down round negotiation. The best valuation is the highest one whose expectations you can honestly exceed before the money runs out.
What do founders get wrong about fundraising math?
Optimizing for the headline valuation and ignoring the terms around it, then celebrating dilution they cannot earn back. Do the ownership math across three rounds before you sign the first one.