The İstanbulkart fare is ₺46.20; tapping a contactless bank card, or buying a one-pass electronic ticket from the machine, costs ₺65. On a return trip that is ₺37.60 more - and the ₺165 card pays for itself within about nine rides. Transfer discounts are also limited to cards personalised with a Turkish ID or residence-permit number, so a visitor's card pays the full fare on every leg.
The M11 and the Marmaray are priced by distance, so the turnstile deducts the line's maximum fare when you tap in and refunds the difference when you tap out. The refund reaches cards personalised with a Turkish ID or residence-permit number - an anonymous visitor card gets nothing back, which is how a ₺38-47 ride can end up costing the full maximum. It also means you must tap out even if the barriers are open.
Havaist is the official coach brand for Istanbul Airport (IST) and runs from hava.ist; HAVABÜS is a separate company serving Sabiha Gökçen (SAW) on the Asian side and runs from havabus.com. Buy the wrong one and you have paid for a coach that leaves from an airport 90 km away. The two names are one letter apart and both are sold online.
The M11 runs about 06:00 to 00:00. Land at 01:00 and the cheap option is simply gone, leaving the Havaist coach on its 24-hour routes or a taxi at the metered rate. The metro is also the wrong plan for a tight onward connection, since the M2 change at Gayrettepe adds 20-40 minutes.
The meter is ₺71.94 plus ₺47.92 per kilometre with a ₺230 minimum, and bridge, tunnel and motorway tolls are charged on top - the driver pays them and adds them to your total. There is no airport flat fare and no night surcharge; the same meter applies at 3am as at 3pm. Anyone offering a fixed price inside the terminal is setting their own.