Baggage policy for Greyhound, Megabus, Trailways and more Added up (length + width + height), check-in bags should be no larger than 62 inches or 158 centimeters. The typical size of the overhead compartment in buses is 9x16x20 inches (22.8×40.5×50.8 cm).

The size of the bag you can take on a bus depends largely on the type of service you are using—specifically whether it is a local city transit bus or a long-distance coach like Greyhound or FlixBus. For local city buses, there are no "strict" measurements, but the general rule is that your bag must be small enough to fit on your lap or under your seat without obstructing the aisle or taking up an extra seat that a passenger could use. Most drivers will not allow large trunks or oversized boxes that pose a tripping hazard. For long-distance coaches, you are typically allowed one large "checked" bag to be stored in the under-bus compartment, which usually must not exceed 62 linear inches (length + width + height) and 50 pounds (22.5 kg). You are also allowed one small carry-on bag to bring into the cabin, which must fit in the overhead rack or under the seat in front of you—roughly the size of a standard backpack or a small duffel. If your bag exceeds these limits, you may be charged an "oversize" or "overweight" fee, or in some cases, the driver may refuse to transport the item if the luggage bay is already at capacity.