Check if a day pass is worth it.
A day pass is worth it once the fares you would otherwise pay exceed its price, and the break-even is simply the pass price divided by the effective single fare, rounded up. The effective fare is the part people miss: on networks that charge again for a transfer, a journey involving one change costs two fares, so a pass reaches break-even in half as many journeys as the sticker fares suggest. Count round trips as two. If you are within one trip of break-even, the pass is usually still worth buying for the option value — it removes the incentive to walk a mile rather than pay another fare.
24 Hour Transit Pass
Effective fare = single fare + transfer fee; pay-as-you-go = trips x effective fare; saving = pay-as-you-go - pass price; break-even trips = pass price / effective fare, rounded up
Usually three to four on most networks, since day passes are typically priced at around three single fares. Add transfers and it can drop to two journeys.
It varies and it matters. A rolling 24-hour pass bought at 2pm covers the next morning's commute; a calendar-day pass expires at midnight or at the end of service.