Five minds. One portfolio. Zero noise.
Five minds
A portfolio
Zero noise
Ask in plain language. Elisa puts it in circulation across the team and Cerebro answers with sources, limits and cost. And it gives a verdict, not an «it depends».
History of this desk
Elisa is an artificial intelligence, not a person. Her answers are generated by an AI model.
This is general analysis and not a personalised investment recommendation. The person who invests is the one who decides. The chat may search the internet when the vault does not know the answer (a figure from today, a recent news item); those internet sources nobody has reviewed them and they may be incomplete or wrong, so check them before acting. The five profiles that sign the answers (Elisa, Jorne, Carlos Bárez, Daniel Ferrer, Inés Torres) are specialisms of one single automatic system: they are not people nor registered advisers.
Tools
Note down your positions and watch how they do. Without an account they are stored only in this browser; with an account, they sync across devices.
What leaves your browser
When you ask in the chat, the text of the question and the history of that conversation are sent. If you have saved reading preferences, the vocabulary level and the depth are sent too. Your saved positions they are not attached to the chat; the portfolio and the scenarios use them in their own sections. That is why answers are general and not personalised: Cerebro is not financial advice. Avoid writing personal or financial data that is not needed. The securities search sends the search text and price queries send the symbols. See the privacy policy to find out which providers there are and what else is used.With your session signed in, positions are are stored in your account: they sync across devices and are deleted with the account. Type the name or the ticker and pick from the list so we know exactly which security it is and which exchange it trades on.
Load portfolio from text
One position per line: TICKER [shares] [price]. The comma works as a decimal point. Repeating a ticker updates it.
Your portfolio starts with one position. Add a security at the top and, if you want, the shares and the entry price.
Scenarios
Two hypothetical accounts with the assumptions you set. They do not predict the market nor rely on your portfolio: they show what what you type implies. If a figure is missing, the screen says: n/a and why. Never a zero that can be read as data.
Search by title or subject; not inside the notes.
Saving and planning
Savings goal: how much to contribute each month
The monthly amount needed to reach a specific figure within a specific period, calculated with the assumptions that are entered.
What it does
It starts from a savings goal, an initial capital, a number of years and an assumed annual return, and solves for the constant monthly contribution that takes the balance to the goal. It also shows the total contributed and the part of that total that corresponds to interest, and draws the path of the balance alongside the goal line.
Key concepts
- Constant monthly contribution: the unknown of the account. It comes from the future value equation, imposing that the final balance be the goal, instead of calculating backwards year by year.
- Monthly compounding: the annual return is treated as a monthly rate, the annual rate divided by twelve, and it is applied for 12 months for each year of the term. It is the same convention as the rest of the calculators in this catalogue.
- Estimated interest: the difference between the goal and the total contributed. It is an estimate made with a constant, assumed return, not a forecast of what is going to happen.
- Goal: the target figure. The calculator treats it as data, without adjusting it for inflation or to any specific moment.
- Term: the number of years until the goal. It is the figure that weighs most heavily on the result: lengthening the term lowers the monthly contribution even though the total contributed rises.
Frequently asked questions
Where do the numbers come from?
The goal, the term and the return are figures that whoever uses the calculator types. The return is a modifiable assumption, not a forecast, and the resulting contribution is only valid for that set of numbers.
How is the required monthly contribution calculated?
It is solved from the future value equation of an annuity: A = (M − P · (1+m)^N) · m / ((1+m)^N − 1), where M is the goal, P the initial capital, m the monthly rate and N the number of months. If the return is zero, that expression does not exist and the split is equal: A = (M − P) / N.
What happens if the initial capital already reaches the goal?
The account comes out negative, and the calculator takes it to zero instead of showing a negative amount. The label of the figure then changes to "You already reach the goal with what you have", because negative savings are not a savings plan.
What is the difference between total contributed and estimated interest?
The total contributed is the sum of everything entered: the initial capital plus the monthly contribution over the number of months. The estimated interest is what the assumed return has added to the balance, that is, the goal minus that total contributed.
Why does the contribution come out with so many decimals?
Because the account does not round. Rounding in the calculation would give a prettier and false figure: the final balance would end up a few cents below the goal, and that shortfall would show in every year of the chart.
Are percentages written with the % symbol?
No. The return is entered as a number: 4 means 4 % a year. If you write "4 %", the field is flagged as invalid and the figure disappears, instead of the calculator correcting the figure on its own.
What limits do the fields accept?
The goal and the initial capital run from 0 to 10.000.000 €, the term from 1 to 80 whole years and the return from −100 to 100. An empty field does not equal zero: leaving it blank and typing 0 are two different intentions and the calculator cannot know which one it is.
And if the return is negative?
The formula allows for a negative return, and then the balance stops growing or shrinks. The monthly contribution needed to reach the goal rises accordingly, and if with those numbers the goal falls out of reach the figure reflects that instead of clipping it.
Does the goal take inflation into account?
No. The account works in current euros: the goal and the initial capital are amounts of today and the return you enter is nominal. To read that result in today's purchasing power you have to deflate it, which is what the compound interest calculator does.
Related calculators
Compound interest with inflation
What a savings plan with a monthly contribution will be worth in a few years, in nominal euros and in today's euros. Free and with no sign-up.
Emergency fund
How much money the months of expenses you choose to keep set aside come to, and how much is left to complete them. Free and with no sign-up.
Financial independence
How many years it takes for your assets to cover your annual spending at the withdrawal rate you set. Free and with no sign-up.
Your account
Your portfolio and your saved notes, also on your other devices. Without an account you can keep using the portfolio in this browser. When you delete your account, the associated data is deleted too.
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Adjust how we explain it to you
Two optional questions: your vocabulary level and your preferred depth. They are used to adapt the explanation. We do not ask about amounts of money and we do not run a suitability assessment. The answers are generated by the system and may contain errors; these preferences do not guarantee that the result is identical in every case.