Google already converts currency. Here's the gap.

For one conversion at a desk, nothing beats the search box. The trouble is that travel is not one conversion at a desk.

Type 1500 baht in usd into Google and you get an answer instantly, from a live mid-market rate, for free. As a way to answer a single question while planning a trip, it is close to perfect, and no app improves on it.

The three places it stops working

It needs a connection. This is the obvious one and the most consequential. The moment you are actually abroad — on a plane, in a market, on a roaming plan you are trying not to burn — the search box is not there. Converting is a thing you do most often precisely where connectivity is worst.

It is slow in the physical sense. Unlock, find the browser, tap the address bar, type a sentence, wait for a page, read the answer. That is perhaps fifteen seconds and two hands, in front of someone waiting for you to respond to a price. A converter that opens straight into a keypad is a few seconds and one hand. The difference sounds trivial written down and does not feel trivial at a market stall.

It answers the wrong question. Google tells you that 1,500 baht is about $45. It does not tell you whether $45 is a sensible price for the thing you are being offered. That second question is the one that actually costs travellers money, and no exchange rate can answer it.

What to use instead, honestly

Most travellers end up using at least three of these, and the useful skill is knowing which one the moment calls for.