The 3 numbers investors check first in your financial model
You’ve probably spent more time on your financial model than on almost anything else in your raise. The tabs, the formulae, the five-year forecast that curves into a beautiful hockey stick by year three. You’re proud of it, and you should be, because building one at all is more than most founders manage. So it stings a little when you finally get it in front of an investor and they barely glance at the number you’re proudest of.
I spent my career on the capital side, first across three of the UK’s largest corporate banks and then advising founders through their raises. I’ve opened a lot of models. Here’s the uncomfortable truth about how that first look actually goes: the investor’s eye doesn’t travel to your year-three revenue. It skips straight past it, down to three numbers that tell them, in about ninety seconds, whether the rest of the model is worth reading.
Those three numbers aren’t secret and they’re not clever. But knowing which ones they are, and being able to talk about them without flinching, is often the difference between a second meeting and a polite no. Let me walk you through them, in the order an investor tends to reach for them, and what each one is really asking about you.
Why they skip your headline revenue number
Start with why the big number does so little for you. Your year-three revenue is a forecast, and a forecast is a guess in a suit. Everyone in the room knows you can’t actually know what you’ll sell three years out, so the size of that number carries almost no weight. A very large one can even count against you, because it signals either that you don’t understand your market or that you assume the investor doesn’t.
So the experienced reader does something that surprises most founders. They ignore the output and go hunting for the inputs, the handful of numbers that are harder to invent and that reveal whether you actually understand the business you’re building. Get those right and the forecast becomes believable. Get them wrong, or fail to know them cold, and no amount of polish on the top line will save you.
Number 1: gross margin
The first number the eye lands on is gross margin. In plain terms, gross margin is what’s left out of every pound of revenue once you’ve paid the direct cost of delivering the thing you sold. If a customer pays you a hundred pounds and it costs you twenty to serve them, your gross margin is eighty per cent.
Investors reach for this first because it tells them what kind of business you actually have, before any question of growth. A genuine software business keeps most of every pound, because serving one more customer costs very little. The widely used benchmark for a healthy software business is a gross margin of roughly 70% to 80% or higher. That is an industry convention drawn from public software data rather than a hard rule, and it holds as a benchmark as of July 2026. Sit comfortably in that band and you’re signalling a real, scalable business.
Sit well below it, say at forty or fifty per cent, and you’ve not necessarily done anything wrong, but you have raised a question. It usually means there’s a lot of human delivery, expensive infrastructure, or a chunk of low-margin services tucked inside what you’re calling software revenue. That’s fine for some businesses, but it changes what you’re and how you should be valued, and an investor would far rather hear you explain it than find it for themselves. Know your gross margin, and know why it is what it is.
Number 2: what a customer actually costs you
The second number is about the engine behind your revenue line: what it costs to win a customer, and how quickly you earn that back. Two bits of jargon live here, so let me define them plainly. CAC, or customer acquisition cost, is the total sales and marketing spend it takes to land one new paying customer. The CAC payback period is simply how many months of that customer’s revenue it takes to repay what you spent winning them.
Investors care about payback because it tells them how efficiently your growth is bought. The common benchmark is that recovering your CAC in under 12 months is strong, 12 to 18 months is acceptable, and beyond about two years starts to worry people, because you’re tying up cash for a long time on every customer you add. There’s a companion figure you’ll hear a lot, the LTV to CAC ratio, which compares the lifetime value of a customer to what they cost to acquire. The well-known rule of thumb, three to one or better, was set out by the investor David Skok on his For Entrepreneurs blog around 2010.
Here’s the honest part, and it matters at your stage. That three-to-one rule was drawn from mature, public software companies, and it gets misapplied to early-stage startups constantly. If you have twenty customers and six months of history, you can’t truly know a customer’s lifetime value yet, and any investor worth talking to knows that. So don’t fabricate a precise number to hit a magic ratio. What they’re really checking is whether your revenue forecast is built from the bottom up, customers multiplied by price, with a believable method and cost for acquiring them, rather than a top-down fantasy where you simply capture one per cent of a huge market. Show them the engine, honestly, even if it’s small.
Number 3: your burn and your runway
The third number is the bluntest, and it’s about survival. Your burn rate is how much cash you spend each month, net of anything coming in. Your runway is how many months that cash lasts before you run out. And the raise you’re asking for is, in the investor’s eyes, simply a purchase of more runway.
So the question they’re really asking of your model is whether this raise gets you somewhere that matters. The widely followed convention is that a round should buy roughly 18 to 24 months of runway. That’s not arbitrary. Raising takes four to six months of its own, and you need a year or so of clear execution in between to hit the milestones that justify the next round. A raise that only buys six or nine months tells an investor you’ll be back, cap in hand and out of options, almost before the ink is dry.
So don’t size your raise around a number that sounds impressive. Size it around a milestone. The simple way to express it: your monthly burn, multiplied by the months you need to reach a genuine next milestone, plus a buffer of roughly half again for the things that always go wrong. State plainly what the money buys, in milestones rather than months, and your ask suddenly looks considered rather than plucked from the air.
What these three numbers are really testing
Step back and you’ll notice these numbers aren’t really about the spreadsheet at all. Gross margin, customer cost and burn are the investor’s way of finding out whether you understand your own business at the level someone about to hand you money needs you to. A founder who can talk about their margin, their payback and their runway without reaching for the file is telling the investor something no forecast can: that they’re in control of the thing they’re building.
That’s also why you should never hand your model off to the point where you can’t defend every line of it. It’s completely fine to get help building it. It’s not fine to be unable to answer “why is that number what it is?” in the room. The model is not the deliverable. The conversation it makes possible is.
One note before you act on any of this. The benchmarks above are widely used conventions, not laws, and they shift with the funding climate; the figures here hold as general benchmarks as of July 2026. None of this is regulated financial advice, it is the view of someone who has sat on the other side of the table. Your own numbers, and a qualified adviser where the stakes are high, come first.
Before you send your model to anyone
If you want to know how your model reads before an investor sees it, that’s exactly what the Launchology Funding Readiness Assessment is built to do. It looks at where you stand, these three numbers included, and tells you honestly what an investor would flag first, so you can fix it on your own time rather than in a pitch. Take the Funding Readiness Assessment.