Free tools for index investors
Index investing is simple to explain and hard to sustain. What eats long-term returns is almost never the choice of index: it is the fees you never checked, the tax toll of a badly timed rebalance, and selling in the worst month of a drawdown.
These tools take on one of those decisions each, and answer a single question. They are free, ask for no sign-up, and run in your browser: nothing you type leaves your device.
TER Calculator
What do my funds really cost me?
Works out the weighted average TER of your portfolio and projects, over 40 years, how many euros fees take away. Useful for choosing between two funds separated by a seemingly innocent 0.10%.
Open tool →DecisionIs it time to rebalance?
Do I act now or wait?
Four questions — drift, time since your last adjustment, tax cost and fees — and a verdict. Built for the moment you see your portfolio skewed and cannot tell whether the fix costs more than the problem.
Open tool →RiskCrash simulator
Could I actually sit through a drop like that?
Applies real historical crashes to your capital — the 2000 bubble (−49%), Lehman in 2008 (−56%), COVID in 2020 (−34%) — and estimates how long recovery would take, with and without contributions. It is a behavioural tool, not a forecast.
Open tool →AccountingAverage price calculator
What did I really pay for this?
Weighted average purchase price from your own transactions, counting sells, dividends and fees. For anyone who has been contributing for years and lost track of their real cost basis.
Open tool →What order to use them in
You do not need them all, nor in this order. But if you are building the portfolio now, this is the path that avoids the most expensive mistake at each stage.
-
Cost first — the only certain number
Nobody knows an index's future return; its fee is written down. It is the only variable in your portfolio you can fix today and that will hold for the next forty years, so it is where to start. A 0.10% difference on €100,000 is not €100 a year: it is €100 the first year, plus the compounding of every year after that.
-
Then, whether anything actually needs moving
Seeing your portfolio skewed is not reason enough to touch it. Rebalancing has three costs — fees, spread, and a tax toll if it forces a sale — and some drifts are cheaper to live with than to fix. The decision depends on how far you have drifted, how long you have been there, and whether you can correct it by contributing rather than selling.
-
The crash, before it arrives
The question in a crisis is not how far the index falls, it is whether you stay. A −56% like 2008 means nothing in the abstract; against your capital, with your number, with the months recovery would take, it does. Use it cold, when nothing is happening: during the fall it is no longer a simulation, it is a decision.
-
And finally, what you actually hold
After years of instalments, with the odd sale and dividend in between, almost nobody knows what price they actually paid. Without that number there is no way to tell whether you are up, or to work out what you would owe the tax office the day you sell. It is accounting, not opinion.
Frequently asked questions
- Do they work if my portfolio is not an 80/20?
- Yes. You set the weights: two funds or nine, with whatever percentages you decided. None of the four assumes a particular allocation or suggests a different one.
- Do they cover index funds and ETFs?
- Both, with one difference that matters in Spain: you can transfer between mutual funds without triggering tax, while an ETF tracking the same index cannot. That changes what a rebalance costs, which is why the tax question sits inside the checklist.
- What figures do I need to hand?
- Not much: the current value of each holding and its TER for the cost one, your targets for the checklist, and your purchases with dates and amounts for the average price. No passwords, no connecting your broker.
- Does this replace an adviser?
- No, and none of them tells you what to buy. They compute the consequences of decisions you have already made — what a fee costs, what a rebalance would cost, what you could sit through in a crash — so you decide with the number in front of you instead of on a hunch.
Why free and with no sign-up?
Because a calculator that asks for your email before giving you a number is not a calculator, it is a form. None of these tools store what you type or send it to a server, and there is no paid tier behind them. If you want full portfolio tracking — your transaction ledger, live prices and the exact split of every contribution — that is the app, and it is free too.
See the rebalancing calculator