Ask someone how much they spend in a month. Not what they earn, what they spend. Almost nobody can answer within a few hundred euros. Now notice what that means: they are making every financial decision of their life, how much to save, whether they can afford the flat, whether a job change is survivable, whether they could handle three months without work, on top of a number they do not know.
That is not a character flaw. Nobody ever sat them down and said: before any of the interesting stuff, find out what your life costs. So that is this article. One temporary project, one number at the end of it, and then the correct order to build everything else on top.
Track for a season, not for life
First, the reassurance, because it changes whether you start at all: this tracking is temporary. Two or three months, then you stop.
You are not becoming a person who logs receipts forever. Tracking forever is the detailed-budget trap from the previous article, the tool that runs on guilt and dies within weeks. What you are doing here is different in kind: a measurement, not a lifestyle. The way a doctor takes your blood pressure to learn a number, you are taking two or three months of readings to learn yours. Once you have it, the cuff comes off.
The method matters less than the honesty. Export your bank and card statements for the last two or three months, or track fresh months as they happen, whichever you can face. Put every expense into rough piles: housing, utilities, groceries, transport, insurance, debt payments, and then everything else. Do not round the ugly ones down. The whole value of this exercise is that the numbers are yours, not the ones you would like to have.
Two months is the minimum because any single month lies. One has a birthday in it, another has an annual bill, a third is weirdly quiet. Two or three months averaged gets you close enough, and remember the standard from earlier in this series: close enough, acted on, beats precise and postponed.
The number you are hunting for
Out of the piles come two figures.
The first is what your life costs as you actually live it: everything, fun included, per month. Say your tracking shows €1,850.
The second, the more important one, is your essentials floor: what one month costs if you strip it to what you genuinely could not cancel. Rent, utilities, groceries, transport, insurance, minimum debt payments. Say those look like this:
| Essential | Per month |
|---|---|
| Rent | €650 |
| Utilities | €120 |
| Groceries | €300 |
| Transport | €100 |
| Insurance | €80 |
| Phone and internet | €50 |
| Other non-negotiables | €100 |
| Essentials floor | €1,400 |
That €1,400 is your number. It is the minimum monthly income that keeps your life standing, and it quietly answers questions you have been guessing at for years. Could you take a lower-paid job you would love? Compare its take-home pay to €1,400 plus your goals, and the question becomes arithmetic. How big does your safety net need to be? You are about to see that it is a multiple of exactly this figure. What income does "enough" start at for you? Now you know, to the euro, instead of vaguely suspecting it is "more."
Until you know what one month of your life costs, every financial decision you make is a guess wearing a confident face.
The famous frameworks, in plain words
Once people start measuring, they meet the two famous frameworks, so here they are without the mystique.
50/30/20 says: put 50% of take-home pay toward needs, 30% toward wants, 20% toward savings and debt repayment beyond minimums. On €2,000 a month, that is €1,000, €600, and €400. Its virtue is that you can hold it in your head. Its limit is that it was designed for nobody in particular: in an expensive city your needs may eat 65% and the neat split collapses, and it has no opinion about what the 20% should do first.
Zero-based budgeting says: give every euro a named job until income minus assignments equals exactly zero. Nothing is "left over," because leftover money is unmanaged money. Its virtue is total intentionality. Its limit is the price of that intentionality: it is the high-maintenance end of budgeting, and for most people it decays into the app-graveyard pattern from the previous article.
| 50/30/20 | Zero-based budgeting | |
|---|---|---|
| The idea | Three fixed shares of take-home pay | Every euro assigned a job, down to zero |
| Effort | Minutes per month | Hours per month, ongoing |
| Suits | Beginners who want one simple rule | Detail-lovers, tight or irregular incomes |
| Breaks when | Your rent does not respect the 50% | Life gets busy and logging stops |
Use them as lenses, not laws. 50/30/20 is a quick sanity check on your tracked numbers. Zero-based is a philosophy worth stealing one idea from, which we will, two sections down. Neither replaces knowing your own numbers, because both are generic and your rent is not.
The number sizes the buckets
Here is where the measurement pays off. The previous article gave you the four buckets: fixed costs, savings, investments, guilt-free spending, with rough starting ranges. What it could not give you was your split, because that depends on numbers only you can measure. Now you have them, and the buckets size themselves.
Your essentials floor is the fixed-costs bucket: €1,400 on €2,000 of take-home pay is 70%. That is above the suggested 50 to 60% range, and that is fine, it is a fact, not a grade. It simply means the other buckets share €600 for now: perhaps €300 to savings, €100 to investments, €200 guilt-free, and a note to work on the biggest fixed line over time, because no amount of skipped coffees moves a €650 rent.
This is the whole relationship between the two articles: tracking is the measurement, buckets are the machine. You measure for two or three months, set the machine, and stop measuring. From then on the plan runs on payday autopilot, and you only re-measure when life changes shape: a move, a raise, a child.
The waterfall: what to fund, in what order
Knowing your number also settles a question that paralyzes beginners: with limited money, what comes first? The answer is an order of operations. Water fills the top pool before it spills into the next.
First: the essentials. Housing, food, utilities, transport, minimum debt payments. Obvious, but stating it matters, because every later step is funded only by what spills over the €1,400, never by what is carved out of it.
Second: the emergency fund. A separate savings account holding three to six months of your number. This is why the number matters so much: "three to six months of expenses" is empty advice until you know your expenses, and then suddenly it is a euro amount. Three to six times €1,400 is €4,200 to €8,400. A vague aspiration just became a target you can track, and at €300 a month it is reached in 14 months. It lives in a boring savings account, not in investments, because its one job is to be there, unshrunk, on the worst week of your year.
Third: tax-advantaged accounts, where your country offers them. Many countries provide special containers, pension schemes or investment accounts, where savings grow with lighter taxes as an incentive for long-term saving. The concept is generic even though the acronyms are local: same money, same investments, less tax drag, usually in exchange for locking the money up or capping the yearly amount.
| Country | Examples |
|---|---|
| UK | ISA, SIPP |
| US | IRA, 401(k) |
| France | PEA |
| Greece | No ISA-style equivalent; occupational and private pension schemes exist |
Availability and rules vary a lot by country, so this step is one evening of reading what exists where you live. A later article in this series returns to retirement accounts properly.
Fourth, and only now: ordinary investing. Money that is invested for decades, on top of a funded life and a full emergency fund. Everything this blog says about investing later assumes the first three pools are full.
Why the emergency fund outranks the market
The order is not a style choice, and the emergency fund's position is the least negotiable part of it.
Invested money moves. Over long periods that is the point, but in any given month the market can be down 20 or 30%, and it does not consult your calendar. Now imagine a bad month with no cash buffer: the car dies, or the job does. Your only source of money is your investments, so you sell, and you sell whatever the price happens to be that week. A temporary market drop becomes your permanent loss, not because you panicked, but because your transmission did.
The emergency fund is what makes that sequence impossible. With four months of your number sitting in cash, a €900 repair is an annoyance handled from savings, and your investments stay untouched through the dip, which is the entire trick of long-term investing. People say the emergency fund earns nothing. In truth it earns you the ability to never be a forced seller, and forced selling is where ordinary savers take their worst, most avoidable losses.
Sinking funds: December stops being a crisis
One refinement, borrowed from zero-based budgeting because it is that philosophy's best idea: the sinking fund, for the bills that are perfectly predictable and still manage to ambush you every year.
Annual insurance, car service, holidays, gifts in December. None of these are emergencies, you knew they were coming, they come every year. The fix is to divide by twelve and set the money aside monthly:
| Irregular bill | Per year | Set aside monthly |
|---|---|---|
| Annual insurance | €300 | €25 |
| Car service | €240 | €20 |
| Summer holiday | €900 | €75 |
| Total | €1,440 | €120 |
That €120 a month lives in the savings bucket, quietly building. When the insurance renewal lands, the money is already there and the month absorbs it without a ripple. No raided emergency fund, no credit card bridging "just this once," and December arrives as a month instead of a crisis. The emergency fund is for the bills you could not see coming. Sinking funds make sure the ones you could see coming never touch it.
Spend from the plan, not the balance
A short habit that separates people this system works for from people it does not: stop asking your account balance for permission.
"There is money in the account, so I can afford it" is how careful people quietly overspend, because a running balance is a lie of availability. It shows one number that is secretly many: next week's rent, the sinking funds, the half-built emergency fund, and only then anything spendable. Spend against the total and you are spending money that already has a job, you just cannot see the assignment.
The discipline is to spend from the plan instead: the guilt-free bucket, the named sinking fund, the assigned category. This is why the previous article suggested separate accounts, one job each. When the guilt-free account is the only one your daily card touches, its balance actually means what a balance seems to mean, and the question "can I afford this?" gets an honest one-glance answer.
Net worth: the one number for the long run
Tracking spending is temporary. One measurement is worth keeping forever, because it takes five minutes a quarter: your net worth.
Net worth is everything you own minus everything you owe. Cash, savings, investments on one side; loans, credit card balances, any other debt on the other. Say you have €4,200 in the emergency fund and €1,800 invested, and €1,200 remaining on a loan: €6,000 minus €1,200 is a net worth of €4,800.
Write it down four times a year, and do not judge the level, watch the direction. Month to month it wobbles and the wobble means nothing. Quarter over quarter, year over year, it is the single honest scoreboard of your financial life: income you did not keep never shows up in it, and neither does spending you pretended was an investment. Everything else in personal finance is detail in service of one sentence: net worth, gently and persistently, going up.
A brief, honest word on insurance
One gap this article should not leave open. The emergency fund covers the small shocks, the €900 repair, the two lean months. It cannot cover the catastrophic ones: serious illness, disability, liability for harm to someone else, a home disaster. Those arrive with costs that no six months of expenses will absorb, and insurance is the only tool sized for them.
This series does not sell insurance and will not tell you which policies to buy; needs differ wildly by country and situation. But the principle belongs here: insure the losses you could not recover from, self-insure the ones you can, using the fund you are now building. Skipping catastrophic coverage to save a monthly premium is the one omission that can undo every other step on this page at once.
The foundation everything else stands on
Notice what you have at the end of this project, none of it glamorous: what your life costs, an essentials floor, buckets sized to reality, a funded order of operations, and one scoreboard checked quarterly.
Every article that follows in this series leans on that foundation. You cannot judge a credit card without knowing whether you can clear it monthly, which is a question about your number. You cannot size an investment plan without knowing what spills over your essentials and your emergency fund. And you cannot make a sane decision about any of the exciting stuff, stocks, funds, retirement accounts, until "what do I need to live?" has a numeric answer instead of a nervous shrug. Investing built on an unknown cost of living is a house built on an unmeasured slope. The measuring is two or three months of mild tedium. Do it once, and everything built afterward stands straight.
Do this now
This week, open your banking app and export the last two full months of transactions. Put thirty minutes on the calendar, sort the expenses into rough piles, and write two figures on one line: what your life cost as lived, and your essentials floor. That second figure, multiplied by three, is your first emergency-fund target. You now know your number, and you are already ahead of almost everyone who never measured.
Next in the series: Credit cards and debt, the tool that is a convenience at 0 days and a treadmill at 20% a year, and how to keep it on the right side of that line.