Your bank balance tells you where you are. It says nothing about where you are heading. A big tax bill, a quiet summer, a client who always pays late: they are all visible weeks in advance, if you bother to look forward. A short forecast is how you look forward.
Why thirteen weeks
Thirteen weeks is one quarter, and it is the sweet spot. Long enough to catch the bills and slow patches that a monthly view misses, short enough that you can actually guess the numbers with a straight face. You are not predicting a year. You are lighting up the road just far enough ahead to brake or turn in time.
Build it in a single sheet
You do not need software. A simple grid with a column for each of the next thirteen weeks does the job.
- Start with today's cash. That is your opening balance for week one.
- Add money in. For each week, list what you genuinely expect to collect, based on who owes you and when they usually pay, not when the invoice says.
- Subtract money out. Rent, wages, suppliers, tax, the lot. Put each cost in the week it actually leaves.
- Carry the balance forward. Each week's closing balance becomes the next week's opening one.
Now read down the final row. Any week that dips toward zero or below is a warning light, glowing weeks before the problem arrives.
A forecast does not stop bad weeks from coming. It just stops them from arriving as a surprise.
The habit that makes it work
A forecast is not a document you build once and file. It is a living view you update.
Spend ten minutes each week: shift everything along by one column, drop in what actually happened, and extend a fresh week onto the end. This rolling habit keeps the picture honest and always looking a full quarter ahead.
When a week lights up red, you have options precisely because you saw it early. Chase an invoice now, delay a purchase, lean on your cushion, or line up a deposit. Seen in time, a crunch is a decision. Seen too late, it is a crisis.
Open a blank sheet this week, map your next thirteen weeks, and put a standing ten-minute slot in your calendar to keep it rolling.