Every new business plan asks for a sales forecast, and every new owner finds it hard. With no history, you are predicting the behaviour of customers who have not yet bought. The answer is not to avoid forecasting but to do it carefully, in a way that you can test and improve. A forecast is a set of assumptions written down, and the better the assumptions, the better the forecast.

Start from customers, not from hope

The weak way to forecast is to say that the market is huge and you will capture one percent. The stronger way starts from the ground up: how many customers can you actually serve, how often will they buy and how much will they spend? For a shop, that might be the number of people passing, the share who come in, the share who buy and the average basket. For a service, it might be the number of clients you can handle each week and the price per job.

Break the forecast into pieces

Write the forecast as a chain of numbers: visitors, conversion rate, average sale, repeat rate. A shop that expects 200 visitors a day, a 15 percent buying rate and an average sale of KES 800 forecasts 200 × 0.15 × 800 = KES 24,000 a day. Each piece can be checked on its own, and you can see which piece matters most. If the buying rate is 10 percent instead, the answer changes by a third.

Find evidence for each number

Get real data wherever you can. Count foot traffic at the location on different days. Visit similar shops and see what they sell. Ask suppliers what comparable customers buy. Run a small test, such as a market stall or a pre-order, to learn real conversion rates. Even a rough test is more reliable than an estimate from your head. Importing from China: risks and checks shows a similar careful approach to testing a product before committing.

Allow for a ramp-up

New businesses rarely start at full speed. Customers need to hear about you and try you. Build a ramp-up into the forecast, with lower sales in the first months and growth as awareness builds. Be careful about growth rates: a forecast that grows twenty percent every month for a year has you at nearly nine times your starting sales.

Build three scenarios

Prepare a cautious, an expected and an optimistic version. In the cautious case, sales are lower and costs stay as planned. The question is whether you can survive the cautious case, and for how long. Plan your cash around it. The 12-month cash flow forecast and cash flow forecast for a small business show how to turn sales into cash.

Sales alone do not make a plan. Subtract the cost of the goods and the fixed costs to see the profit. Use the break-even and pricing calculator to find the sales you need each month to cover costs, and compare with the forecast. If you need more sales than seems realistic, change the plan before you start. Break-even analysis for small businesses explains the method.

Remember tax

Expected sales determine which tax regime applies. If you expect to pass the VAT threshold, plan for registration; use the VAT registration checker. Small sales may fit turnover tax; test it with the turnover tax calculator. Include the tax in your cash planning. Starting a business: registration and tax steps lists what to set up.

Use the forecast to decide

A forecast is useful when it changes a decision: how much stock to buy, how many staff to hire, how much to borrow. A bank will want to see your assumptions; how to prepare your business for a bank loan application shows what lenders look for. The sales forecast and target planner turns assumptions into monthly targets.

Update it as real sales arrive

The most important step comes after launch. Compare actual sales with the forecast every month, find out which assumption was wrong and fix it. After a quarter, you have real data and can build a much better forecast for the next year. Treat the first forecast as a first draft. Businesses that learn quickly from the gap between plan and reality are the ones that survive their first years.