Where the cost actually is
Three places. First, the spread on every conversion (typical retail: 0.4-1.5% one-way, sometimes more). Second, the currency drift on holdings - if you live in EUR but hold GBP equity, the FX move is part of your return whether you like it or not. Third, the cost of being unable to see net worth in a single currency, which leads to over- or under-saving against goals.
The first you can manage with tooling. The second is unavoidable but should be a conscious decision, not an accident. The third is a pure visibility problem.
Pick a base currency and stick to it
Decide which currency is your 'home' - usually the one you receive most of your income in or in which most of your liabilities are denominated. Net worth, savings goals and emergency funds should all be tracked in that currency. Holdings in other currencies show up in the dashboard as their base-currency equivalent, with the FX rate flagged.
This sounds obvious. In practice many UK-based investors with USD-listed equities track everything in dollars in one app and pounds in another and never reconcile. The drift can be 5-10% over a couple of years before anyone notices.
Tooling: the FX layer
For day-to-day cross-currency conversions and holdings, the standard 2026 stack is some combination of:
- Wise (formerly TransferWise) - mid-market rates plus a small explicit fee. Multi-currency account holds GBP, EUR, USD and another forty-plus currencies natively.
- Revolut - similar offering, with margins above mid-market on weekends and high-volume tiers requiring premium subscriptions for unlimited free FX.
- Multi-currency brokerage at Saxo, IBKR, Interactive Brokers - useful for holdings, not for everyday spending.
- Card-only solutions (Curve, native bank multi-currency cards) - simple but typically less competitive on rates than Wise/Revolut.
Hedging investments - usually no
Most retail investors should not hedge equity FX exposure. The reason is that equity returns over decades dominate the FX noise - you are paying 0.1-0.3% a year for the hedged share class to remove a factor that is much smaller than the asset volatility you are taking anyway. The exception is if you hold significant fixed income in a non-base currency - bond yields are not large enough to absorb FX moves, so currency-hedged bond exposure is the standard.
If you are within five years of a defined liability (house deposit, retirement) and the asset is held in a non-home currency, consider partial hedging or convert progressively. This is less about tooling and more about timing.
Visibility: one number, multiple currencies underneath
The single most useful thing a multi-currency-aware net-worth app does is give you one base-currency total at the top, with the underlying currency split visible one click down. Bank AI does this; most single-bank apps do not, because they only see their own currency. If you keep money in more than one currency the cost of not having this view is real - it is the gap between knowing what you have and pretending to.