Most founders know they need a financial model. Far fewer know what actually goes in one, or how to build something an investor won’t immediately pick apart.
This is a practical guide to what matters, what to include and how to avoid the traps that catch founders out at the worst possible moment – usually three days after a VC asks for your supporting financials.
What is a startup financial model?
A financial model is a spreadsheet-based representation of how your business is expected to perform financially over time. It typically covers a three to five year horizon and includes projected revenue, costs, cash flow and the assumptions behind each.
The honest truth is that every financial model is wrong. Your actuals will never match your projections exactly. The point is not precision – it’s the discipline of thinking through your business clearly enough to put numbers on it. If the process of building your model reveals a flaw in your plan, that’s the model doing its job.
Start with your plan, not your spreadsheet
The most common mistake is opening Excel before you’ve mapped out how the business actually works. Your model is a financial translation of your plan – it can only be as solid as the thinking behind it.
Before you touch a formula, get clear on:
- How you acquire customers and at what cost
- How revenue is generated (one-off, recurring, usage-based)
- What your key cost drivers are – headcount, infrastructure, marketing
- When you expect to reach cash flow break-even
Once that’s clear, the numbers follow naturally.
What to include in your financial model
A solid startup financial model has three core outputs and a set of assumptions that drive them.
Profit and loss (P&L) Your projected revenue minus your costs, showing whether the business is heading toward profitability and on what timeline.
Cash flow forecast Profit and cash flow are not the same thing. A business can be profitable on paper and still run out of money. Your cash flow forecast shows when cash comes in and goes out, and how much runway you have at any point.
Balance sheet Less critical at early stage but increasingly important as you scale or approach a raise. It shows what the business owns, what it owes and the net position.
Assumptions tab Every model needs one. All key inputs – growth rates, conversion rates, pricing, headcount timing – should live in a single assumptions tab, not buried in formulas. If an investor finds a hard-coded number tucked inside a formula, they’ll wonder what else they haven’t found.
How to make your assumptions credible
Investors will push on your assumptions harder than anything else. “We’ll grow 20% month on month” needs to be backed by something.
If you’re pre-revenue, use industry benchmarks as your starting point – conversion rates, average contract values and churn rates for comparable businesses in your sector. If you have trading history, use it. Your own data is always more credible than an industry average.
Build bottom-up where you can. Rather than assuming a lump-sum marketing spend, model out your actual channels and their expected returns. It takes longer but it forces better thinking and holds up better under scrutiny.
Practical spreadsheet design tips
A model that’s hard to read is a model that erodes investor confidence. A few simple rules make a big difference:
- Colour code inputs vs formulas – use one consistent colour (blue is common) for cells a user can change, and keep formula cells in black. This makes the model navigable for anyone who picks it up.
- Use graphs – a visual of your revenue growth, burn rate or runway is far easier to absorb than a wall of numbers. Overlay actuals against projections if you have trading history.
- Keep it appropriately detailed – too simple and it looks like you haven’t thought it through; too complex and no one can follow it. Match the level of detail to your stage.
What investors actually want to see
Your financial model is supporting material, not a pitch deck. Most investors won’t want it in the room – they’ll ask for it afterwards if they’re interested.
What they’re assessing is whether you understand your own numbers. Can you walk through your revenue assumptions clearly? Do you know your unit economics? Can you explain why your burn rate looks the way it does?
A tight, well-structured model signals that you’ve thought seriously about execution – not just vision. We’ve seen deals fall over because a founder took three weeks to “clean up” a model after an investor requested it. Have it ready.
Need help building or pressure-testing your financial model? Our team works with founders at every stage – from first-pass models to investor-ready financial forecasts. Talk to us about financial modelling.
