Daily cap / capping
What it really means
With contactless or Oyster in London, once your fares reach a daily maximum ("the cap"), the rest of the day is free. There is a weekly cap too if you use the same card all week.
Context, tips & common mistakes
Capping quietly does the maths for you, but a few details decide whether you actually benefit. The daily cap depends on the zones you touch, so one detour through Zone 1 raises the whole day's cap; the weekly cap runs Monday to Sunday, not any seven days, and only builds if you use the same card or device all week — switching between a phone and the physical card splits your record and can cost real money, since a phone and its linked card count separately. Visitors using foreign bank cards should check their bank's per-transaction foreign exchange fees, which can quietly exceed the fares; an Oyster card avoids that. Capping never requires signing up to anything, but creating a free TfL account and registering your card lets you see journey history and claim refunds. Note that caps cover TfL services and most National Rail within London, but airport premium services like Heathrow Express sit outside the cap.