How to start a forecast on a piece of paper

Looking ahead at your money sounds like it should require software. It doesn't. Software helps once your forecast has more than ten or twenty things in it, but for the first one, paper is faster.

Here's the whole method.

The five steps

1. Write down today's bank balance. The actual number that's in your main account right now. Put the date next to it.
2. List every payment you know is coming out in the next 30 days. Rent, subscriptions, a bill you got in the mail, a friend you owe, a flight you booked. Put the date next to each one and the amount.
3. List every payment you know is coming in in the same 30 days. Paychecks, refunds, money someone owes you. Date and amount.
4. Sort all of those by date — incoming and outgoing together, in order.
5. Walk down the list. Start from today's balance. For each event, add it (income) or subtract it (outgoing). Write the new balance next to it. Keep going. This is your running balance — the number that tells you what you'd have if nothing changed.

The number at the bottom is what you'll have at the end of the period — assuming nothing changes, which it will, but that's fine. You're not predicting the future perfectly. You're getting a clearer picture than zero, which is what most people start with.

A worked example

Imagine it's the morning of April 1. You have $1,800 in your main account. Here's what you know is coming over the next 30 days:

That's it. Less than ten minutes of work, and you now know two things you didn't know before:

• You'll dip to $674.52 between April 5 and April 15. If anything else lands in that window, you need to think hard about it. If nothing does, you're fine.
• By April 30 you'll have about $2,760. Anything you want to do with that money — save it, spend it, set it aside for next month's rent — you can decide on purpose, not by accident.

Common questions when you do this

"What about variable spending — groceries, fuel, going out?"

For your first forecast, don't try to predict every coffee. Pick one rough number for "everything else" — say $400 a week, or whatever your honest guess is — and treat it like a single weekly outgoing event. You'll refine it later.

"What if a number I wrote down was wrong?"

You cross it out and write the right one. The forecast was never going to be exact. The point is to be approximately right, not perfectly right.

"How often should I redo it?"

Once a week is plenty. Five minutes on a Sunday: cross out anything that already happened, add anything new you've learned about, recalculate the running balance. That's the whole maintenance.

"How far ahead should I go?"

Start with one month. Once that feels easy, go three months out — that's where yearly bills start to show up and the forecast becomes really useful. Six months and beyond is for big decisions like moving or changing jobs.

If you'd rather not redo this every week

Once you've done this on paper a couple of times, you'll notice most of the work is repetition: the same recurring charges, the same paychecks, just shifted forward by a month. That's exactly the part a tool can do for you.

Forgettie is the version of this for your phone. You enter each recurring payment once — name, amount, how often, next due date — and it keeps the running list sorted by date for you. New month, same list, dates shifted. The math doesn't have to be redone.

Next 30 days+

Starting balance $1,800.00

Apr 1 Rent − $1,100 $700.00

Apr 4 Streaming app − $15.49 $684.51

Apr 5 Music app − $9.99 $674.52

Apr 15 Paycheck + $2,400 $3,074.52

Apr 20 Cloud storage − $12.00 $3,062.52

Apr 25 Insurance renewal − $300.00 $2,762.52

End of month $2,762.52

One more idea: working backwards from a goal

The forecast you just learned looks forward from today. The same idea works in reverse: pick something you want money for, put a date on it, and figure out what each month between now and then needs to look like.

For example: you want a $1,200 trip in eight months. That's $150 a month, starting now, that you need to be setting aside. If your forecast says the average month leaves you with $200 left over, you can do it. If it says $80, you can't — not without changing something else first.

Pick one thing you want money for. Put a date on it. Work backwards. That's the whole method.

Forgettie has a savings goals view that does this math automatically. You enter a goal amount and a target date; it tracks how much you've put aside so far, how much is left, and how long it'll take at your current pace. The math underneath is the same — Forgettie just keeps the running totals updated as your forecast updates.

The point

A forecast is never finished. Life keeps changing, so the forecast keeps updating. That isn't a flaw — it's the entire skill. You're not trying to know exactly what's going to happen. You're trying to never be surprised by something you already knew was coming.