How much can I spend today: the only number worth looking at
A budget with twelve categories is useless at the supermarket till. One number is not.
In short
Today's figure is worked out like this: what came in this month, minus everything obligatory for the month, minus what you are going to save, minus what you have already spent on the rest; the result is divided by the days left in the month. It recalculates daily, so an expensive day shrinks the following ones by itself and there is no need to punish yourself. If it comes out negative, the month's free money is gone and the answer is zero, not a small number.
A well-built budget has twelve or fifteen lines and answers questions nobody asks while standing in a shop perfectly well. The question people do ask there is a single one, and it has a numerical answer.
The calculation, in full
What came in
This month, really
What reached the account, not gross pay
Minus the obligatory
The whole month, not what is paid
Housing, utilities, transport, debts, subscriptions
Minus the saving
Up front, not afterwards
What is left at the end of the month is never left
Divided by the days left
And recalculated daily
An expensive day shrinks the following ones by itself
What remains after the three subtractions is the month's genuinely free money. Divided by the days remaining, it is today's figure.
Why the whole month is subtracted, not what is already paid
This is the detail that makes it work, and the one almost every spreadsheet skips.
Rent is paid on the 5th. If on the 3rd you only subtract what has been paid so far, that day's number is enormous and untruthful, and on the 6th it collapses. The figure has to subtract the whole month from day one: the obligatory is already committed even if the charge has not gone out yet.
With that correction the number is stable. Without it, it rises and falls with your suppliers' billing calendar, which has nothing to do with you.
Why it divides by the days left
Because that spreads errors instead of accumulating them.
You overspend on a Saturday. The next day the number is slightly smaller, and that is that: the month has already rebalanced without you deciding anything or feeling bad. And if a day passes with no spending, the next one rises a little. The system corrects itself daily, which is something a monthly budget does once and too late.
When it comes out negative
The honest answer is zero, not a small figure.
A negative number means the month's free money has gone, and what you spend today comes out of savings or out of debt. That is not a disaster and is best seen that way: it is information arriving in time, on the 22nd, while there are still eight days that can be lived differently.
What hurts is not finding out until the 30th.
What this number does not do
It does not tell you whether your budget is well set up, does not point out where your money goes, and does not replace looking at categories once a month. It is a tool for an immediate decision, not for analysis.
The analysis goes separately and monthly: where does my money go is about that. Together they are the whole system, and neither works without the other.
Common questions
- Why does my daily figure change every day?
- Because it is recalculated from what is left of the month and the days remaining. An expensive day reduces the following ones slightly and a day without spending raises them: the month corrects itself, instead of the whole adjustment arriving on the 30th.
- Is rent subtracted before I have paid it?
- Yes, from the first day of the month. If it were only subtracted when paid, the figure would be enormous for the first few days and then collapse: the obligatory is already committed even if the charge has not gone out.
- What do I do if the number comes out at zero or negative?
- It means the month's free money is spent and today's would come out of savings or debt. Finding out on the 22nd is the useful part: eight days remain that can still be lived differently.
Try it on your own money
Caudal is an expense tracker in Spanish, English and Russian. Several currencies, goals, debts, a shared household budget. Recording an expense takes three seconds.
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