Currency
The euro, and Frankfurt is where the European Central Bank actually sets policy for it. That does not protect you from dynamic currency conversion, which is worse here than almost anywhere because of the airport and station traffic: terminals and cash machines will offer to bill you in Canadian dollars at their own rate. Always decline and pay in euro. Avoid the freestanding Euronet machines in the Hauptbahnhof concourse and around the Zeil; withdraw inside a bank branch.
Cards and cash
For Germany's financial capital, Frankfurt runs on a surprising amount of cash. Contactless works in supermarkets, department stores and larger restaurants, but apple-wine taverns, Kleinmarkthalle stalls, Imbiss counters, kiosks and some taxis take cash or the domestic Girocard only, and no German business is obliged to accept your Visa or Mastercard. Carry euro notes and keep coins — station toilets and the ones at the airport want them.
Tipping
Round up rather than compute a percentage; five to ten per cent covers good table service. The mechanism is the part Canadians get wrong: German card terminals generally do not offer a tip screen, so you tell the server the total you want charged before they process the card. In an apple-wine tavern where the Bembel keeps arriving, settle up at the end and round the whole thing. Cash tips handed over directly are preferred.
Power and plugs
Type F Schuko sockets, round and recessed with earth clips at the sides; Type C europlugs fit the same hole. Mains is 230 volts at 50 hertz, roughly double Canada's 120. Phone and laptop chargers marked '100–240V' just need an adapter; Canadian hair dryers, straighteners and travel kettles marked 120V only will fail, sometimes spectacularly. A bulky North American grounded plug will not seat in a recessed socket, so buy a proper Schuko adapter.
Water and language
Tap water is safe throughout Germany under the Trinkwasserverordnung — fill your bottle from any tap, including at the airport. Restaurants still expect to sell bottled water and a request for Leitungswasser may be politely turned down, so do not plan on free tap water with a meal. Frankfurt has one of the highest shares of residents with foreign roots of any big German city and English is spoken almost everywhere, but the local dialect is Hessian and the apple-wine vocabulary is worth knowing before you sit down: Ebbelwoi, Bembel, Geripptes, Schoppen.
Safety
Frankfurt is safe by any Canadian standard, with one district that genuinely warrants specific advice rather than generic caution. The Bahnhofsviertel between the Hauptbahnhof and the banking towers has an open drug scene concentrated on Taunusstrasse, Elbestrasse, Moselstrasse and parts of Niddastrasse; by day it is busy and manageable, at night it can feel unpleasant, and the standard local advice is to stick to Kaiserstrasse and the well-lit main roads rather than cutting through side streets. Pickpocketing follows the usual pattern at the Hauptbahnhof, on the airport S-Bahn and in Zeil crowds — keep bags in front of you on the S8 and S9 with your luggage, which is exactly where opportunists work.