Based on the sales targets you define using the TAM SAM SOM model the next step is to estimate all costs that are needed to build or deliver your product or service and all expenses that are needed to perform all sales and marketing, research and development, and general and administrative tasks for your company to stay alive.
When estimating these you obviously aim for profitability within a reasonable timeframe. In other words: at some point all costs and expenses should not exceed your revenue targets anymore so that you get to a positive EBITDA (earnings before interest, taxes, depreciation and amortization).
Bottom up forecasting
The pitfall of the top down approach is that it might seduce you to forecast too optimistically (especially sales). Often entrepreneurs calculate SOM (equal to sales) by taking a random percentage of the market, without really assessing whether this target is realistically achievable.
A tiny percentage of a market might seem insignificant, but could be way too optimistic for instance in the year of your launch. Therefore, it could be useful to complement the top down method with the bottom up approach.
The bottom up approach is less dependent on external factors (the market), but leverages internal company specific data such as sales data or your company’s internal capacity. Contrary to the top down method, the bottom up approach begins with a micro/inside-out view and builds towards a macro view. This means a projection is made based on the main value drivers of your business.
Short example: let’s assume one of the main drivers of an online SaaS business is online marketing. One of its online marketing tactics is to advertise its product via LinkedIn. The company could define the costs per click using LinkedIn’s advertising tool, estimate the number of website visitors it will attract as a result, the conversion from website visitor to a lead, and the conversion from lead to customer.
Based on these metrics the company will have a good idea of potential sales, of course constrained by the budget available for online advertising. Performing a bottom up analysis therefore does not only force you to think about what are realistic targets for your company, but also to think about the ways in which you will spend your resources.
With the bottom up approach, you estimate revenues, costs, expenses and investments in the same way as described above: based on the resources at hand and the company data that is available. The pitfall of the bottom up method though is that it might fail to show the optimism needed to convince others of the potential of your company.
If you are a startup founder and you are looking to raise funding, the bottom up approach might not do the trick. Investors usually expect startups to grow fast and gain significant market share rapidly. The bottom up method might fail to reflect that.
It is difficult to create a forecast with a steep growth curve if every sale has to be rationalized and if its point of departure is the maximal capacity of your company (or budget for advertising purposes). With the bottom up approach it is hard to take into account factors such as virality or word of mouth. Moreover, the whole reason why external financing is needed, is often to expand capacity and grow faster than a company would do organically.
Therefore, when you build your startup’s forecast it could be advisable to combine both the bottom up and top down methods, especially when you plan to achieve a strong growth curve by means of external funding. Use the bottom up method for your short term forecast (1-2 years ahead) and the top down method for the longer term (3-5 years ahead). This makes you able to substantiate and defend your short term targets very well and your long term targets demonstrate the desired market share and the ambition an investor is looking for.
Assumptions
No matter what approach you use to build your startup’s financial model, it is crucial you are able of substantiating your numbers with assumptions. As a startup, historic data is often not available so you need to be able to present the ‘proof’ behind your numbers.
This will also help you when you start discussing with investors, as they are typically interested in knowing the reasoning behind your numbers. They are considering to put money in your company, so you do not want to give them the feeling you are selling baloney!
Assumptions can be anything that validate your numbers: market research, web search volume, contracts with suppliers, pricing validation, historic sales, conversion rates, bills of materials, website traffic, etc. It could be useful to create a “data room” (e.g. a Drive folder) in which you collect these kinds of evidence. By doing so, you are slowly building a library that underpins all the numbers you have put in your model and you are well prepared in case an investor might request a due diligence process.
Now, that is more than enough background to get started. Let’s get to it: the financial overviews a good financial model (of a startup) should include!