Anyone starting a budget reaches the same question within a few minutes: how much is it normal to spend on each thing? How much on groceries, on the home, on going out? One answer turns up everywhere, and it is the 50/30/20 rule.
It is a good rule and deserves to be known. But it was designed around a level of income and a cost of housing that do not match many households in Portugal, and applied to the letter it can make your budget feel wrong when it is only being honest.
This piece explains the rule, shows where it stops working with dated figures, and suggests a way of reaching your own limits that survives the real month.
What is the 50/30/20 rule?
A split of net income into three slices.
- 50% for needs: housing, bills, groceries, transport to work, health. What you would still pay in a month where you cut everything else.
- 30% for wants: going out, restaurants, clothes beyond what you need, holidays, subscriptions, hobbies.
- 20% for savings: the emergency fund, goals, paying down debt.
The rule's strength is its simplicity. Three numbers, easy to remember, giving a first answer to "am I spending too much?". And it has a merit that should not be underrated: it makes saving a slice of the month, rather than whatever is left at the end, which is nearly always nothing.
Why does the 50/30/20 rule fall short?
Because the needs slice is not something you choose, and on low incomes it passes 50% on its own.
With Portugal's 2026 minimum wage, 920 euros gross a month on the mainland, take home pay for someone with no other deductions is close to 819 euros after the 11% social security contribution. The 50/30/20 rule applied to that gives:
| Slice | % | Amount |
|---|---|---|
| Needs | 50 | 410 |
| Wants | 30 | 246 |
| Savings | 20 | 164 |
Four hundred and ten euros for housing, bills, food and transport. A rent of 450 euros is enough for the home alone to exceed the whole slice, before a single electricity bill or trip to the supermarket. The rule is not wrong; it is describing a month that, for this person, does not exist.
With two incomes and a shared rent the sum improves, which is why the rule works well in many two-person households. But the underlying issue stays: needs are a cost, not a choice, and the rule treats them as a percentage that adjusts.
So how do you decide how much to spend per category?
From your typical month, not from a rule.
The starting point is not what you should spend, it is what you do spend. Take the last three months, add up what went to each category, and pick the typical month: not the average, which one unusual month spoils, and not the best month, which only happened once. The full method for estimating a cost that varies is in fixed and variable expenses.
That typical month is your first limit, category by category. It sounds unambitious and it is meant to: a limit your normal month already meets is a limit you will manage to keep, and a limit kept for three months teaches more than an ambitious one abandoned in the second week.
Only once the limits hold do you start moving them, and that is where the 50/30/20 rule becomes useful again.
What is the 50/30/20 rule good for, then?
For seeing which way to move, not for saying where you must be.
Group your categories into the rule's three slices and look at your real percentages. The comparison tells you one of three things:
- Needs are well over 50%. The problem is not going out or coffee. It is housing, transport or income, and that is where a change makes a difference, even if it is big and slow.
- Wants are over 30% and savings are near zero. There is room, and it is in the decided spending. This is the case where cutting makes sense, and where seeing where your money goes usually shows where.
- All three slices are close to the rule. The budget is balanced, and the work is keeping it there, not squeezing it.
Used this way, the rule is a diagnosis. Used as a fixed target, it is a source of guilt for anyone who cannot meet the first line.
How much to spend per category when savings cannot reach 20%?
Start with a percentage you can keep, and raise it with every pay rise.
Twenty per cent savings is an excellent target and, for many people, impossible in the first year. That is no reason to save nothing. A budget that saves 5% every month is far better than one that tries 20% and gives up in February.
The technique that works is to make saving the first expense of the month, not the last, with an automatic transfer on the day you get paid. And every time your income rises, part of the rise goes straight into that transfer, before the month gets used to it. After a few years the 20% arrives without any month having hurt.
The first destination for savings, ahead of any other goal, is the emergency fund, and how much it should hold is in emergency fund: how much, where to keep it.
How many categories do you need to know how much to spend?
Few, and the right number is the one you can keep up.
With twenty categories, every purchase forces a decision about where it goes, and half the categories end up with two movements a month and limits that say nothing. With five or six, each has enough volume for the limit to mean something.
A list that works for most households: groceries, home and bills, transport, going out and restaurants, personal, and one category for whatever fits nowhere else. It is only a starting point; the test is whether you can file a purchase in under two seconds. If you cannot, there are too many categories.
Where to start deciding how much to spend, today
Three steps, and the second is the one that matters.
- Add up the last three months by category. Few categories, five or six. Pick the typical month for each one.
- Set that typical month as the limit, and leave it for three months. No cuts yet. The aim is a limit that gets met.
- Group the categories into the 50/30/20 rule's slices and read the diagnosis. High needs, high wants, or balance. It is the direction of the next adjustment, not an obligation to make it now.
We keep a page of frequently asked questions about budgeting and everyday money, with a short answer to each one and the full piece one click away. If you want to see it, it is here: frequently asked questions.
Figures from October 2026. The numbers in this piece refer to that date.
This is educational writing. It is not financial advice or an investment recommendation; for advice on products, speak to a professional registered with the CMVM.