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Calculadora Capital

Invest with Your Head: the series

Twelve articles, four acts, one promise: every number comes from a calculator you can run with your own figures. No forecasts, nothing to sell.

3 min readReviewed By Thorben Rasmus IdelReviewed by Nahar Geva

TL;DR

Invest with Your Head is a twelve-article series on saving and investing in Portugal, built on evidence rather than forecasts. In four acts it shows what leaving money idle costs, what the data say about funds and ETFs, how to build a simple portfolio and how to take the first step. Every number comes from a calculator on this site, with the assumptions in plain sight.

What is the Invest with Your Head series?

A twelve-article path for people who want their money to work without becoming experts, following tips or placing bets. The thesis is simple and has decades of evidence behind it: for most people, what decides an investment's outcome is not picking the right moment or the right stock, but the costs you pay, the time you give your money and the ability not to bail out halfway1.

The series adapts the theses of passive investing, popularised in German by Gerd Kommer4 and backed by academic research and by the annual reports that compare managed funds with the indices they try to beat12, to the Portuguese reality. That reality means deposits and savings certificates as the starting point, PPRs sold over the counter, the 28% withholding tax, IRS on capital gains and a culture that treats the family home as the default investment.

Why are the numbers the centre of the series?

Because promises cannot be checked and numbers can. Every euro figure in the series comes from a calculator on this site, with the assumptions written next to it. Three examples, all at 6% gross a year with monthly contributions:

ScenarioResult
300 € a month, 30 years, ETF at 0.2% vs. fund at 1.5%about 62 000 € less with the fund (290k vs. 228k)
100 € a month from 25 vs. 300 € from 40, both to 65199k vs. 208k, but the first put in 48k and the second 90k
200 € a month, starting 10 years laterabout 146 000 € less

What these numbers say, in order of importance: the product's cost weighs more than the choice of bank or broker, and the date you start weighs more than the amount. That is why the series talks about the problem first and about brokers only at the end.

How is it organised?

Four acts, three articles each. Published articles appear as links; the rest follow in the order shown.

1.The problem

  1. 01What leaving your money in the bank really costs (coming soon)
  2. 02Nobody can time the market — and that is good news (coming soon)
  3. 03The invisible cost: how 1.5% a year eats a third of your retirement (coming soon)

2.The evidence

  1. 04Active funds or ETFs? What 20 years of data say (coming soon)
  2. 05Diversification: the only free lunch (coming soon)
  3. 06Gold, Bitcoin and your home: three "safe investments" that are not what they seem (coming soon)

3.The method

  1. 07The World Portfolio: a simple portfolio with one or two ETFs (coming soon)
  2. 08How much risk can you take? The question that decides your portfolio (coming soon)
  3. 09Markets fell 30%. Now what? (coming soon)

4.Taking action

  1. 10Start early: €100 at 25 earns almost as much as €300 at 40, with less than half the money (coming soon)
  2. 11How to choose a broker in Portugal without overpaying (coming soon)
  3. 12Your first investment in 30 minutes, step by step (coming soon)

What the series is not

It is not financial advice. It recommends no specific stocks, funds, ETFs or brokers. It explains mechanisms, shows what the data say and gives you the tools to do your own sums. Where a topic involves products, the link goes to our comparison pages, which state their criteria and use the figures the providers publish. Everyone's situation is different; for weighty decisions an independent professional can add value.

Where to start?

If you have money sitting in an account, start with the first article of act 1. If you already know you want to invest and only need a method, skip to act 3. Either way, the compound interest calculator lets you see in seconds what the series discusses over twelve articles.

Frequently asked questions

Who is this series for?
Anyone with money in deposits, savings certificates or a bank PPR who has never bought an ETF and wants to see, in numbers, whether and how it is worth changing. No stock-market knowledge needed.
Does the series recommend a product or a broker?
No. It explains mechanics and shows your numbers. Where products are involved it links to our comparison pages, which state their criteria and use figures published by the providers themselves.
Where do the numbers come from?
From this site's calculators, which use tested formulas, and from primary sources cited in each article: Banco de Portugal, CMVM, INE, the SPIVA scorecards by S&P and Morningstar's Barometer.
In what order should I read?
By act: the problem first, then the evidence, then the method, then action. Each article links to the next, but each also stands on its own.

Related reading & calculators

Sources

  1. 1.SPIVA Europe Scorecard · S&P Dow Jones Indices
  2. 2.Active/Passive Barometer · Morningstar
  3. 3.Inquérito à Situação Financeira das Famílias (household finance survey) · Banco de Portugal
  4. 4.Souverän investieren mit Indexfonds und ETFs · Gerd Kommer, Campus Verlag

Author / Reviewed by

Author

Thorben Rasmus Idel

Co-founder & writer

Co-founder of Calculadora Capital and the writer behind the methodology on every calculator and article. An entrepreneur and active investor, Thorben founded Idel Versandhandel GmbH, an international trading company operating across 16 countries, and invests across stocks, ETFs and cryptocurrency. He writes the methodology and verifies the math behind each page, drawing on hands-on business and investing experience to keep the tools and explanations grounded in how money, markets and taxes actually work for everyday people in Portugal.

Reviewed by

Nahar Geva

Co-founder & reviewer

Co-founder of Calculadora Capital and the independent reviewer behind every calculator and article. An entrepreneur and active investor, Nahar brings a data- and product-driven mindset together with hands-on experience in the markets, investing across stocks and ETFs as well as cryptocurrency and other digital assets, alongside broader personal finance and real estate. On each page Nahar reviews the methodology and double-checks the math and figures, pressure-testing how the tools and explanations hold up against the way money, markets and taxes actually work for everyday investors.

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