Your startup's runway — the number of months until you run out of cash at your current burn rate — is arguably the single most important metric in your business. It determines when you need to raise, when you need to cut, and how much risk you can afford to take on any given decision. Yet most founders check it once a month at best, using a spreadsheet that's already stale by the time they open it.
The number you need is simple: (cash in bank) / (net monthly burn) = months of runway. The hard part is getting accurate inputs. Revenue fluctuates. Expenses have timing issues (that annual insurance payment hits in March and distorts the whole month). And the spreadsheet you built six months ago has assumptions baked in that no longer reflect reality.
Why spreadsheet runway tracking breaks
Most founders track runway in one of three ways, all of which have problems:
The bank-balance-divided-by-vibes method: You look at your bank balance, estimate monthly burn from memory, and divide. This works until it doesn't — usually right when you need the number most (a board meeting, a fundraise decision, a hiring call).
The monthly spreadsheet ritual: Once a month, you pull numbers from Stripe, download bank statements, categorize expenses, calculate net burn, and update the spreadsheet. This is accurate but stale — by mid-month, the number is two weeks old. And you skip it when you're busy, which is exactly when you should be watching it closest.
The QuickBooks P&L approach: You wait for your bookkeeper to close the books, then look at the P&L. This is tax-accurate but 3-6 weeks behind reality. Your runway could have changed materially in that window.
What live runway tracking looks like
The modern approach is to connect your revenue source (Stripe) and your bank accounts (via Plaid) to a tool that calculates burn and runway automatically from live transaction data. Here's what that gives you:
Daily accuracy, not monthly
Your burn rate is recalculated from the trailing 30 days of actual bank transactions every day. When a large bill hits, your runway adjusts immediately — you don't discover it three weeks later in a spreadsheet.
Expense breakdown by category
Instead of one "burn" number, you see where the money goes: payroll, software, marketing, rent, professional services. This matters because knowing your burn is $80k/month is less useful than knowing $40k is payroll, $15k is software, and $10k is ad spend you can cut tomorrow.
Forward projections
A trailing burn rate plus your current cash balance gives you a projection: at this rate, you have X months. Most tools project 12-24 months forward, which lets you see not just when you run out, but when you cross various thresholds (6 months of runway, 3 months of runway — the points where you should be acting).
Scenario layering
The real power: what happens to your runway if you make a specific decision? Hire two engineers ($25k/month burn increase). Raise prices (revenue goes up 15%, churn goes up 5%). Cut ad spend ($10k/month burn decrease). Each of these can be modeled against your live baseline.
The metrics that matter
Beyond raw runway, track these:
- Net burn rate: total expenses minus total revenue for the trailing 30 days. This is your actual cash consumption rate.
- Gross burn: total expenses before revenue. Useful for understanding your cost structure independent of sales.
- Revenue growth rate: month-over-month revenue trajectory. If it's growing, your runway is extending even if burn is flat.
- Cash position: total cash across all accounts. Simple but critical — it's the numerator in the runway equation.
When to act
The common thresholds:
- 12+ months: comfortable. Make decisions without panic.
- 9-12 months: start thinking about your next raise or path to profitability. This is the time to prepare, not to panic.
- 6-9 months: actively raising or cutting. If you're raising, you should already have conversations started. If you're cutting, decide what goes now.
- Under 6 months: you're in the danger zone. Every decision should be viewed through the lens of extending runway. This is where the spreadsheet-once-a-month approach kills companies — by the time you notice, you're already in trouble.
Getting started
Starch Runway Analysis connects to Stripe and Plaid, calculates your burn rate and runway from live data, and shows a 24-month projection updated daily. Pair it with Scenario Analysis to model hiring decisions, pricing changes, and fundraise timing against your actual baseline.
Once you have runway visibility, the next step is automating your investor updates so the same financial data feeds polished reports to your LP list.
Both are available in closed beta. Request access to get started.