How do I forecast revenue with no trading history?

The backward method is the common one and it is where most first year forecasts go wrong. Somebody decides ninety thousand is the number, divides by twelve, and writes seven thousand five hundred against every month. It is arithmetic rather than a forecast, and it produces no information when the months do not match, because there was never a mechanism behind it.

The forward method builds from things you can influence. If you expect twenty enquiries a month and convert one in four at an average of eight hundred, that is four thousand. Every one of those numbers can be checked against reality within a quarter, and when the total is wrong you can see which input caused it.

Where the inputs come from with no history is the obvious objection. Use whatever is closest. What you charged at a previous employer or in a previous role. What comparable businesses in your area appear to charge. What you have already quoted, even if nothing was won. The response rate on anything you have already sent out. All of these beat a guess and none of them require a trading history.

Build three versions rather than one, because a single number carries a false precision. A cautious case where things go slowly, an expected case, and an optimistic one. The useful test is the cautious case: if the business still functions there, the plan is fundable. If only the optimistic case works, you have a plan that depends on everything going right.

Ramp the early months rather than starting at full rate. A business that will eventually do twenty enquiries a month will not do that in month one, and a forecast assuming otherwise is wrong in a predictable direction. Building the climb in explicitly is more honest than applying a general discount at the end.

Include the seasonality you already know about. Most trades, retail categories, and professional services have quiet periods that are entirely predictable, and forecasting a flat year guarantees the forecast is wrong twice. If you do not know your seasonality yet, say so and revisit after two quarters.

Forecast costs on the same basis, separating those that rise with sales from those that do not. Materials, processing fees, and contractor time move with volume. Rent, insurance, and software do not. A forecast that treats them the same is unusable for any decision about pricing or capacity.

Then compare against actuals monthly and correct the inputs rather than the total. If enquiries were as expected but conversion was half what you assumed, the problem is the sales conversation rather than the marketing. That diagnosis is the entire value of forecasting this way, and it is unavailable from a forecast built by dividing a target by twelve.

Expect the first two quarters to be wrong and treat that as normal. A forecast is a set of assumptions written down so they can be tested, and the version you produce after six months of real figures is the one that starts being useful.

Keep the forecast somewhere you will actually open, and update the actuals monthly rather than quarterly. A forecast reviewed twice a year is a document, and the value of the method is entirely in the correction.

Note the assumptions alongside the numbers so the reasoning survives. Six months from now you will not remember why you assumed a one in four conversion rate, and without that note you cannot tell whether the assumption or the execution was wrong.