What a multi-currency net worth tracker has to get right

A multi-currency net worth tracker has to store each transaction with the exchange rate from the day it happened, not today's rate, and give each account, holding, budget and transaction its own currency, so history stays fixed while net worth still reports in the one currency you think in. The tracker also has to keep the underlying amounts in their own currencies, because without them no chart can show how much of a net worth change was your money and how much was exchange rates. Hundo's net worth chart shows that split.

If you hold money in more than one currency, most personal finance apps are quietly lying to you. Not on purpose - they just made a simplifying choice years ago, and the choice does not survive contact with a second currency.

The choice is this: store one number per transaction, in one base currency, converted at whatever the rate was when you looked.

Why is today's exchange rate the wrong rate?#Link to this section

Say you live in the euro area, earn in dollars, and had a €50 dinner last September when the rate was 1.10. You spent $55. That is a historical fact and it is finished.

Convert at today's rate instead, and if the rate has moved to 1.20 the app tells you that dinner cost $60.

It did not. And the number will be different again next week.

The consequence is worse than one wrong dinner. Every total that includes that transaction moves every day. Last year's spending is not a fixed figure any more. A budget you came in under is one you blew, or the other way round, depending on when you open the app. You cannot compare two months, because the exchange rate underneath both of them has changed.

The fix is not complicated. Record the rate that applied on the day the transaction happened, and store it with the transaction. History then stays still, which is the entire point of writing it down. Which rate to record for a card purchase - the one you saw, or the one you were charged - is its own question, answered in which exchange rate to record.

Why is net worth harder to track in more than one currency?#Link to this section

Spending is the easy half. Net worth in more than one currency is harder, because it moves for two completely different reasons and they look identical on a chart.

Your net worth went up 3% last month. Was that because:

1. You earned more than you spent, or your investments rose, or
2. the currency your savings sit in strengthened against the currency you think in?

The first is you doing well. The second is arithmetic. An app that folds both into one line and calls it "net worth" cannot answer the only question worth asking, which is whether you are actually getting anywhere.

You need the underlying amounts kept in their own currencies, with the conversion applied as a view rather than baked into the stored value. Otherwise the information needed to separate those two causes has already been thrown away.

To see that split for a single investment, the free currency-adjusted return calculator takes what you paid, what it is worth now and the two exchange rates, and shows how much of the return was the holding and how much was the currency.

Which four things need their own currency?#Link to this section

Most tools that advertise multi-currency support have one currency field, on the user. That is the root of it. In a real multi-currency life, currency belongs to each thing separately:

The account. A euro current account and a sterling savings account are different objects. Neither should be stored as "dollars, converted".

The holding. An index fund bought in dollars and gold priced in dollars but bought with euros both need a purchase currency alongside a current one, or profit and loss becomes meaningless - you end up comparing a euro cost against a dollar value and calling the difference a gain.

The budget. If you rent in one currency and buy groceries in another, one budget in one base currency cannot describe either of them honestly.

The transaction. And this is the one almost nothing supports: a transaction may be in a currency the account does not hold. You pay with a euro card in a shop that charges in pounds. That is one transaction, two currencies, and a rate that applied on that day.

Get all four right and one thing falls out for free: a single net worth figure, in the currency you actually think in, that does not change when you are not looking.

How does Hundo handle multiple currencies?#Link to this section

We build one of these, so here is ours specifically, and you should check anything that matters to you.

• 166 currency codes are supported. We say "over 160" because that number is conservative.
• Accounts, assets and individual budgets each carry their own currency, as their own field, not as a display preference.
• Every transaction stores the exchange rate that applied on its own date, at ten decimal places. The stored history does not move when the market does.
• A transaction can be in a currency its account does not hold, with the rate recorded for that day.
• Assets keep a purchase currency alongside their current one, so profit and loss is computed between comparable numbers rather than across a silent conversion.
• Net worth reports in your base currency, converted for display, with the underlying amounts left alone.

Multi-currency was not a feature added later here. It is the reason the data model looks the way it does, and it is the thing we would defend hardest against any comparison.

On question 4 below - how much of a net worth change was exchange rates - this page originally said we did not answer it. We do now. The net worth chart splits the change over the selected period into the part that came from your money and the part that came from the rates moving, because every daily snapshot already stored the per-currency amounts and that day's rates. It shows nothing at all if you hold a single currency, since there would be no split to make.

Does Hundo connect to your bank?#Link to this section

No. Hundo does not connect to banks and does not use an aggregator, so every entry is one you add. It keeps that quick: suggestions ranked from your own history fill an entry in one tap, and a statement file imports in one pass. In Pro, a receipt can also be photographed or forwarded to a personal receipts address, or an AI agent drafts the entry for you to confirm.

If you want a feed to fill the ledger in for you, that is a real thing to want, and there are apps that do it well - within the countries their aggregators cover.

How do you check a tool's multi-currency support?#Link to this section

Whatever you end up using, four questions will tell you how deep its multi-currency support goes:

1. Can an account hold a currency that is not my base one? If not, stop here.
2. When I look at last year's spending, is the number the same tomorrow? If it moves, it is converting at today's rate and your history is not fixed.
3. Can a single transaction be in a currency the account does not hold? This is the one that separates real support from a display setting.
4. Can it tell me how much of my net worth change was exchange rates? If not, its net worth chart cannot answer the question you are asking it. This is the one almost nothing does, and it is the reason the other three matter: without per-currency amounts and the historical rates, the split cannot be computed at all, however much anyone wants it.

Most apps that say "multi-currency" pass the first and fail the rest. It is worth ten minutes finding out before you put two years of history somewhere.

Common questions#Link to this section

Should a finance app convert old transactions at today's exchange rate?#Link to this section

No. Converting at today's rate makes every total that includes a transaction in another currency move every day, so the app should record the rate that applied on the day the transaction happened and store it with the transaction.

How many currencies does Hundo support?#Link to this section

Hundo supports 166 currency codes, and says "over 160" because that number is conservative. Accounts, assets and individual budgets each carry their own currency.

Can a transaction be in a different currency from its account?#Link to this section

In Hundo, yes: a transaction can be in a currency its account does not hold, with the rate recorded for that day. That is the check that separates real multi-currency support from a display setting.

Can Hundo show how much of a net worth change was exchange rates?#Link to this section

Yes. Hundo's net worth chart splits the change over the selected period into the part that came from your money and the part that came from the rates moving. It shows nothing if you hold a single currency, since there would be no split to make.