Note: all the Google searches from this post are enclosed by brackets. For example, you should type usd= when you see [usd=]. If you use google.com instead of your country's Google domain, replace "your country's currency" with "US dollar".
1. The quickest way to convert almost any currency to your country's currency is to search for the currency code, followed by "=". For example [gbp=] for British pounds or [czk=] for Czech koruna. You can also search for [100 gbp], [50 czk], so "=" is no longer necessary when you add a number.
2. The quickest way to convert US dollars to euros is to search for [$], but you can also search for [usd=]. Search for [$100], [100$] or [100 usd] to convert 100 US dollars to euros.
3. The quickest way to convert a currency to any other currency is to type the two currency codes. For example, you can search for [gbpeur], [gbp eur] or [gbp to eur] to convert British pounds to euros. This also works when you search for [100 gbpeur], [100 gbp eur] or [100 gbp to eur].
4. To convert multiple amounts of money in different currencies to your country's currency, use a query like [50 gbp + 100 czk + 200 sek]. To convert them to another currency, use a query like [50 gbp + 100 czk + 200 sek = eur].
5. If you don't know currency codes, your queries will be a bit longer, but you can perform any conversion using a single query. Some examples:
[sweden to euro]
[50 sweden = euro]
[sweden to dollar]
[100 sweden = $]
[swedish to japanese currency]
[sweden to japan currency]
[swedish to indian money]
[sweden to india money]
6. You can use multiple currencies when performing simple arithmetical calculations even if you don't know currency codes. For example, search for [50 uk currency + 100 czech money + 200 dollars=euro].
7. After performing any simple currency conversion, Google shows an interactive widget that lets you change the amount of money or the currencies. You can click the currency name to select a different currency from a long list.
8. How to quickly swap the two currencies? Let's assume you search for [1 yen to yuan] and you realize that you need to convert the Chinese yuan to the Japanese yen. Click the "Japanese yen" drop-down and select "Chinese yuan" from the list. Google places the currencies you use at the top of the list.
9. The shortest query that shows Google's currency calculator is [$], but you can also search for [currency], [currency converter], [currency calculator].
10. You can also use currency names instead of codes and country names. For example, search for [lira to real], [1000 forint to pound], [500 yuan to canadian dollar], [500 peso to ringgit]. By default, peso=Mexican peso, crown=Czech koruna, dollar=US dollar, pound=British pound sterling.
11. Google's currency conversions aren't very precise. By default, Google only shows results with 2-digit precision and that's not always enough. If you search for [algerian dinar in eur], Google shows that "1 Algerian Dinar equals 0.01 Euro". To get a precise result, use a simple trick that forces Google to use the old interface: divide by 1 and search for [1 algerian dinar in eur/1]. The new result: 1 Algerian dinar = 0.00964425063 Euros.