Your whole business, one connected model.

What a founder financial model is

A founder financial model connects the metrics that, in a real startup, move together: the revenue you earn, what each customer is worth, what they cost to acquire, how long your cash lasts, and what the business is worth. Standalone calculators answer one question at a time. A model shows cause and effect across all of them at once.

Most founders first meet these numbers one at a time — an LTV calculator here, a runway spreadsheet there, a back-of-envelope valuation multiple somewhere else. Each answer looks reasonable in isolation. The problem is that none of these numbers actually move in isolation. Cut your price and ARPU drops, which drags LTV down, which compresses your LTV:CAC ratio, which makes your current CAC look worse, which changes how efficiently you're burning cash, which changes your runway. A model that keeps these connections visible is what lets you reason about a decision the way an experienced operator or investor would: not "is this number good?" but "what does this number do to every other number?"

That connectedness is also why this page exists as one model rather than fifteen separate calculators bolted together. When MRR, LTV, CAC, runway and valuation all derive from the same handful of inputs, changing one assumption — say, your monthly churn rate — automatically reflows through every dependent figure, the way it actually plays out on your cap table and in your bank balance.

How the chain connects

Customers and price set your MRR, which annualizes into ARR and, at a market multiple, implies your valuation. Separately, your LTV (driven by ARPU, gross margin and churn) and your CAC (spend per new customer) combine into the LTV:CAC ratio and CAC payback period — the two numbers investors use to judge whether growth is healthy. Finally, your cash and net burn set your runway: the clock everything else races against.

Here is the full cascade worked through with the model's default assumptions, so you can see exactly how one set of inputs produces every output on this page:

• Revenue stage. 100 customers paying $100/month each gives you $10,000 in MRR. Annualized, that's $120,000 in ARR ($10,000 × 12).
• Unit economics stage. An ARPU of $100, an 80% gross margin, and a 5% monthly churn rate combine into LTV: ($100 × 80%) ÷ 5% = $1,600 in lifetime gross-margin value per customer. Spending $10,000 in sales and marketing to land 20 new customers in a month means CAC = $10,000 ÷ 20 = $500 per customer.
• Efficiency stage. Compare those two: $1,600 LTV ÷ $500 CAC = an LTV:CAC ratio of 3.2:1 — just above the 3:1 line investors look for. CAC payback works out to roughly 6.3 months — the time it takes the gross-margin revenue from a new customer to repay what it cost to acquire them.
• Survival stage. $600,000 in the bank against a net burn of $50,000 per month gives you $600,000 ÷ $50,000 = 12 months of runway — the window in which all of the above needs to keep improving, or you need to raise again.
• Valuation stage. At a 5x ARR multiple, $120,000 × 5 = an implied valuation of roughly $600,000 — a simple, directional figure, not an appraisal.

Notice how each stage feeds the next: the same customer economics that produced your MRR also drive your LTV and CAC, and the same cash that funds your runway is what an investor implicitly prices when they apply a multiple to your ARR. Nothing here moves on its own — a 1-point change in churn or a $50 change in CAC ripples into several other cards on this page, not just one.

The numbers investors actually look at

A handful of ratios — the ones this model surfaces with benchmark badges — tend to dominate how sophisticated investors and operators size up a SaaS business at a glance:

• LTV:CAC ratio. The headline efficiency metric. 3:1 or higher is the widely cited threshold for healthy unit economics; below 1:1, you are structurally losing money on every customer you sign, no matter how fast you grow. Ratios well above 6–8:1 can sometimes suggest you're under-spending on growth relative to the value you're creating.
• CAC payback period. How many months of gross-margin revenue it takes to recover what you spent acquiring a customer. Under 12 months is generally considered healthy for SaaS; shorter paybacks mean you can reinvest in growth sooner and with less capital risk.
• Runway. How many months of operation remain at the current burn rate before cash runs out. This is the metric that sets your timeline — for fundraising, for hitting milestones, and for how aggressively you can afford to experiment.
• Rule of 40. A widely used shorthand for balancing growth against profitability: your revenue growth rate plus your profit margin should add up to roughly 40 or more. A company growing at 60% with a -20% margin and one growing at 25% with a 15% margin can both clear the bar — the rule simply says that pure growth and pure profitability are both acceptable paths, but anemic versions of both together are not.
• ARR multiple. The rough conversion rate the market applies to translate annual recurring revenue into a valuation. It moves with growth rate, gross margin, retention, and broader market sentiment — which is why it should be treated as an adjustable assumption, not a fixed constant.

None of these numbers is meaningful alone. A 3.2:1 LTV:CAC ratio built on 5% monthly churn is far more fragile than the same ratio built on 1% churn, because the LTV side is more exposed to a small change in retention. Reading the badges on this page together, rather than chasing any single green one, is the more useful habit.

How to use this model

Enter your assumptions on the left. Every result on the right recomputes instantly. The real value of a connected model isn't the snapshot it gives you for today's numbers — it's the scenario thinking it makes cheap. A few experiments worth running on your own assumptions:

• Halve your churn rate. Watch LTV roughly double, and see how much that alone moves your LTV:CAC ratio — often more than any change you could make to pricing or acquisition spend.
• Double your new customers per month. See what that does to MRR and ARR growth, but also notice whether your CAC and burn assumptions still make sense at that pace — faster acquisition usually means faster spending, too.
• Cut your net burn by 20%. Watch your runway extend, and consider what you'd have to give up — headcount, marketing spend, pace of shipping — to get there, and whether that tradeoff is worth the extra months it buys you.
• Raise your ARR multiple assumption. See how sensitive your implied valuation is to a single adjustable number — and treat that sensitivity as a reason to hold the resulting figure loosely.

That ripple — one input touching four or five outputs — is exactly what a connected model exists to show, and it's the same instinct an experienced CFO or investor brings to the table when they hear your numbers.

Common mistakes and caveats

A few habits separate founders who use these metrics well from those who get misled by them:

• Blended CAC vs. paid CAC. Dividing total sales-and-marketing spend by total new customers (blended CAC) looks much better than paid-acquisition CAC alone when a meaningful share of growth comes from referrals or word of mouth. Conflating the two — especially when deciding how much to spend on paid channels — can lead you to over-invest in acquisition that won't scale the way your blended number suggests.
• Gross churn vs. net revenue churn. The churn that belongs in the LTV formula is customer (logo) churn — the rate accounts cancel. Net revenue churn nets cancellations against expansion revenue and can look dramatically better, even negative, in strong businesses. Using the wrong one distorts LTV in either direction.
• Treating the ARR multiple as fixed. Multiples compress and expand with market conditions, growth rates and capital availability — sometimes by half within a year. A valuation built on a multiple that was reasonable eighteen months ago may not be reasonable today.
• Confusing a directional model with a forecast. This page helps you see how assumptions relate to one another, not predict your company's future with precision. Real businesses face seasonality, cohort effects, and one-time events that steady-state assumptions cannot capture.

These figures are educational estimates meant to build intuition about how startup metrics relate — not individualized financial, investment, or valuation advice. Real decisions about fundraising, spend, or company value should involve your own financials in full and, where the stakes are high, an accountant, lawyer, or advisor who knows your business.