Indian train classes are a ladder built from two variables

Two questions, and everything else follows

The class list on an Indian train booking page looks like an alphabet soup until you notice that it is answering only two questions. Is the coach air-conditioned and sealed, or open to the outside? And how many passengers are fitted into a given length of coach? Every abbreviation is a point on that grid.

The density question is the more consequential one for comfort. A sleeping coach laid out with three tiers of berths in each bay carries far more people than one laid out with two, and the difference shows up as headroom, luggage space, queue length at the washbasin and the general noise level, not simply as a number of berths.

The air-conditioning question is partly comfort and partly a change in the character of the journey. Sealed coaches have tinted windows that do not open, which means no dust and no smell of the countryside going past, and a completely different relationship with the landscape. Some travellers pay more to avoid that rather than to obtain it.

The sleeping classes, from most shared to least

The non-air-conditioned sleeper coach is the baseline of long-distance travel in India: three tiers of berths in the main bay, two more along the side of the corridor, windows that open, and no bedding provided. It is sociable and cheap, and on a hot night in the plains it is the better option only if there is a breeze.

The air-conditioned three-tier coach has broadly the same berth layout inside a sealed, cooled shell, with bedding supplied. An economy variant of the same class exists on many services with a slightly denser arrangement. Two-tier air-conditioned removes the middle berth, which converts the lower berth into a usable seat during the day and adds real headroom above.

First class air-conditioned is a different type of accommodation altogether — enclosed cabins of two or four berths with a door, on a limited number of trains. It is the only class where a group can shut themselves in, and it is priced accordingly. Whether it is worth the step up from two-tier depends almost entirely on how much privacy is worth to you on a particular night.

Day trains use a different vocabulary

Services designed to be completed within a day use seated coaches rather than berths, and they follow the same logic. Chair car is airline-style seating in an air-conditioned coach; executive chair car is the same idea with fewer seats across and more room. The unreserved and second-seating coaches are the non-air-conditioned equivalents, with bench seating and, in the unreserved case, no allocation at all.

The important distinction is not comfort but certainty. A reserved seat is yours and appears on a chart; an unreserved ticket entitles you to travel in a designated coach and to whatever space you can find in it. On a busy route that difference is very large indeed.

On the fastest day services the seated classes are the only ones offered, and the journey is closer to a short-haul flight in feel — catering at the seat, a fixed timing, and no expectation of anyone lying down.

Berth position matters as much as class

Within a coach the berths are not equivalent, and experienced travellers care about which one they get almost as much as about the class. Lower berths are convenient and are the only ones usable as a seat during the day, which is why they are allocated preferentially to elderly passengers and to those who request them under the relevant provisions.

Upper berths give privacy and the ability to sleep whenever you like, at the cost of climbing and of limited headroom. Middle berths in a three-tier bay are the least popular, since they can only be folded down when the lower berth passenger agrees to stop sitting up.

The side berths along the corridor are shorter in the older coach designs and sit next to the passageway, so they are noisier and more exposed to people walking past. Some travellers prefer them anyway, because two people travelling together get a self-contained pair.

Choosing sensibly rather than by price

For an overnight journey in winter in the north, the non-air-conditioned sleeper is genuinely cold and the air-conditioned classes are warmer, which reverses the usual intuition. For an overnight journey in the pre-monsoon heat, a sealed coach is not a luxury so much as a way of arriving able to function.

For a daytime journey of six or eight hours, chair car is usually the right answer if it exists on that route, and a sleeper berth used as a seat is a reasonable substitute if it does not. For anything over about eighteen hours, a two-tier coach starts to justify itself even to people who normally would not consider it.

The one piece of advice that holds regardless of class: on Indian long-distance trains, plan for the journey rather than endure it. Water, a means of charging a phone, a padlock and chain if you are in an open coach, and something to eat that does not depend on the pantry car showing up when you are hungry.