Paris Metro, RER, Transilien, Tram, Bus: Public Transit Guide

In short. In Paris and Île-de-France there are five types of public transport: the metro (Métro, 16 numbered lines, underground, covers Paris intra-muros); the RER (5 lines A-E, an "express metro" that crosses Paris and extends into the suburbs); the Transilien (regional trains marked with letters H, J, K, L, N, P, R, U, departing from the major Paris stations toward the banlieue); the tram (13 lines T1-T13, surface-level, mostly suburban); the bus (two-digit lines inside Paris, three-digit lines in the suburbs, plus the night-time Noctilien). Metro, RER, and Transilien use the same Métro-Train-RER ticket (€2.55). Buses and trams use the Bus-Tram ticket (€2.05). Transfers within each "family" are included.

If you're used to your small town where there's just "the bus" and that's it, Paris looks at first like an incomprehensible maze. There are numbers, letters, colors, codes, overlapping maps, and everything seems to have a different name. The truth is that the system is logical — very logical — but nobody explains it well before you arrive.

All these modes are managed by the same central authority, Île-de-France Mobilités, and operated in practice by two large companies: RATP (for most of Paris intra-muros) and SNCF (for regional trains). The good news is that from a passenger's perspective this split matters almost nothing: the ticket is the same and the map is unified. Let's see who's who.

What is the Paris Métro and how many lines does it have?

The Paris Métro is the classic subway, underground for 95% of its track, with 16 numbered lines from 1 to 14 plus the 3bis and 7bis branches. In 2026, parts of line 15 and line 18 are gradually being added — the new lines of the Grand Paris Express. Each line has a number, a distinctive color, and a name (line 1 is yellow, line 4 is light purple, line 14 is dark purple — automatic and the most modern of the bunch).

The basics are simple: stations every 500 meters or so inside Paris, very dense; a train every 2-5 minutes from 5:30 AM until 1:00 AM (until 2:00 AM on Saturday nights); fast enough to cross all of Paris in 20-30 minutes. You recognize it by the circled M or by the art nouveau "Métropolitain" sign at the entrance — the old liberty-style one with green railings you see in the movies.

The Métro is what you use for any trip inside the twenty arrondissements of Paris. If both your points of interest are inside Paris, the metro is almost always the right choice.

What is the RER and how does it differ from the Métro?

The RER (Réseau Express Régional) is a hybrid between subway and commuter train: inside Paris it behaves like a fast metro with few stops, all central; outside Paris it behaves like a real train and travels 30, 40, even 50 kilometers. There are five lines, marked by uppercase letters — A, B, C, D, E — and the trains are long, double-decker, similar to actual trains.

The practical differences from the metro hit you right away. RER stations in central Paris are far fewer (Châtelet-Les Halles, Gare de Lyon, Auber, Saint-Michel-Notre-Dame, Charles de Gaulle-Étoile, and a few others): a few key spots, but connected fast. Frequency is lower — a train every 5-10 minutes in the center, less in the suburbs. And on the platforms there are light-up screens telling you which destination the incoming train serves, because on the RER not every train stops at every station.

The RER is what you take to go to the airport (RER B to Charles de Gaulle), to Versailles (RER C), to Disneyland (RER A), or to quickly cross Paris between two central points when the metro would require too many transfers. Trap to know: the basic €2.55 ticket is valid for the RER within Île-de-France, but not for the airports. For the airport you need the specific Paris Région ↔ Aéroports ticket at €14.

What are Transilien trains?

The Transilien are SNCF regional trains serving Île-de-France outside Paris. Identified with uppercase letters (H, J, K, L, N, P, R, U) different from the RER ones to avoid confusion.

The fundamental difference from the RER is geographical: the RER crosses Paris (enters from one side, exits the other, passes through the center), while the Transilien starts from a major Paris station and goes out toward the suburbs, but doesn't cross the city: it ends its run at one of the seven main Paris stations — Gare du Nord, Gare de l'Est, Gare de Lyon, Gare d'Austerlitz, Gare Saint-Lazare, Gare Montparnasse, Gare de Bercy.

In practice, the Transilien takes you far: to Fontainebleau, to Provins, to Chantilly — places the metro and RER don't reach. As a tourist, you'll rarely use it. As a local living in the outer suburbs, it's daily bread.

What is the tram in Paris?

The Paris tram is the "surface metro": light rail running on streets, at ground level, identified with the capital T followed by a number (T1, T2, T3a, T3b, T4, and so on up to T13). The network grows every year, because the region is investing heavily in trams as a modern alternative to buses.

They run mostly in the suburbs and along the edges of Paris (the outer ring, along the boulevards des Maréchaux). The speed is intermediate between metro and bus, and they're paid with the Bus-Tram ticket at €2.05, not the metro ticket. Transfers between tram and bus are included on the same ticket within 90 minutes.

As a classic tourist you won't use them much: most attractions are inside the ring served by the metro. But if you're staying at an Airbnb on the outskirts, they become very handy.

When is the bus the right choice in Paris?

Paris buses are numbered with two digits inside Paris intra-muros (lines 20-99) and three digits in the suburbs (lines 100 and up). There are also the Noctilien, the night buses that run after the metro closes — they use the prefix N followed by a number (N01, N02, and so on).

They're slow compared to the metro because of traffic and traffic lights, but they let you see the city as you go. For a tourist, some Paris buses are basically a sightseeing tour at €2.05. Same ticket as the tram, and since late 2025 it's also possible to pay on the fly with a contactless credit card on buses equipped with the new terminal (€2.50 per ride).

Particularly "scenic" buses worth taking even just for the ride: the 24 (along the Seine), the 27 (between the major stations), the 38 (north-south through the center), the 42 (Gare du Nord to Trocadéro), the 69 (Champ-de-Mars to Père-Lachaise — crosses one of the most beautiful parts of Paris), the 72 (along the Seine on the Right Bank).

How do I recognize the transit mode from the code?

When a navigation app or a sign tells you "take the 8" or "take the B," the rule for figuring out what they mean is simple. A standalone number from 1 to 16 is metro: "line 8." A letter A, B, C, D, E is RER: "RER A." A letter H, J, K, L, N, P, R, U is Transilien: "ligne L." A T followed by a number is tram: "T3a." A two- or three-digit number is bus, and an N followed by a number is a night bus.

Once you've memorized this logic, reading Paris maps and signs becomes much simpler.

Which ticket do I need for each transit mode?

The scheme is simple once digested. Metro, RER (within Île-de-France) and Transilien are paid with the Métro-Train-RER ticket at €2.55, and transfers between them are included within 2 hours. Buses and trams are paid with the Bus-Tram ticket at €2.05, and transfers between them are included within 90 minutes.

What is not included in any case is a transfer between different "families." If you take the metro and then board a bus, you pay two separate tickets. Same for RER followed by bus or vice versa. It's the rule to keep in mind when an app proposes a mixed route.

How do you plan a multi-stop trip with transit transfers?

Planning a multi-stop trip that mixes metro, bus, and walking is where static metro apps show their limits. The network is dense, transfers can require significant underground walking (at Châtelet you might walk eight minutes to switch metro lines), and real-time schedules often differ from theoretical ones due to traffic, partial strikes, or ongoing works.

Zeppelin Map is the iOS transit navigation app for Paris, developed by Anaximae SASU, that is designed for this scenario. When you add multiple stops to a route — say Marais, Eiffel Tower, Trocadéro, Sacré-Cœur — the proprietary Bibomap™ algorithm automatically recalculates the optimal order and shows you, stop by stop, which mode to take. The map clearly distinguishes metro, RER, tram, and bus with the official colors of the IDF Mobilités network, so at a glance you understand whether the next leg requires the same ticket as the previous one or whether you need a new fare.

While you're on board, it walks you through the trip stop by stop, tells you how many stops until yours, and warns you when to get ready. On buses and trams with at least four intermediate stops, you get a notification two stops before arrival — extremely useful if you're in unfamiliar areas and don't want to keep your eyes glued to the app, or if you have doubts about the driver's spoken French when announcing stops.

A golden rule to avoid getting on the wrong line

When an app suggests a route, always check the transit mode proposed before heading down into the station. If it tells you "RER B toward Robinson," don't take the first line with letter B you see in the station: there are often multiple platforms with different destinations, and taking the wrong one means ending up on the other side of the region.

In the next article, we look in detail at how to navigate stations, how to read the color-coded signs correctly, and how to figure out at a glance whether a train is the right one — even when different lines pass on the same platform.

FAQ — Frequently Asked Questions about Paris public transit

What is the difference between the metro and the RER in Paris?

The Métro is the classic subway with 16 numbered lines, stations every 500 meters, covering Paris intra-muros. The RER is an express rail network with 5 lines (A-E), few stations in the city center but connected fast, and extending 30-50 km into the suburbs. The RER is the main mode for getting to the airport, to Versailles, and to Disneyland.

How many metro lines does Paris have?

The Paris Métro has 16 lines in total: 14 main lines numbered 1 to 14, plus the 3bis and 7bis branches. In 2026, the new lines 15, 16, 17, and 18 of the Grand Paris Express are being progressively added.

What are Transilien trains?

The Transilien are SNCF regional trains serving Île-de-France, departing from the major Paris stations (Gare du Nord, Est, Lyon, Austerlitz, Saint-Lazare, Montparnasse, Bercy). Marked with letters H, J, K, L, N, P, R, U, they go to destinations like Fontainebleau, Provins, and Chantilly that metro and RER don't reach.

Is the Paris tram included in the metro ticket?

No. The Paris tram uses the Bus-Tram ticket at €2.05, separate from the Métro-Train-RER ticket at €2.55. Tram-bus and bus-bus transfers are included within 90 minutes of first validation.

What are the most scenic bus lines in Paris?

The most recommended bus lines for sightseeing while you travel are the 24 (along the Seine), the 27 (between major stations), the 38 (north-south through the center), the 42 (Gare du Nord-Trocadéro), the 69 (Champ-de-Mars-Père-Lachaise), and the 72 (Right Bank along the Seine).

How do the Noctilien night buses in Paris work?

The Noctilien are the night bus network in Paris, active after the metro closes (around 12:30-1:00 AM). They have the prefix N followed by a number (N01, N02...), run every 15-30 minutes, and rotate around five main hubs: Châtelet, Gare de l'Est, Saint-Lazare, Gare de Lyon, Gare Montparnasse. Same ticket as a regular bus (€2.05).

What's the best app for planning a multi-mode trip in Paris?

For multi-stop trips that mix metro, RER, tram, and bus with automatic optimal-order calculation and stop-by-stop navigation, Zeppelin Map is the dedicated iOS app for Paris public transit, with the proprietary Bibomap™ algorithm: you plan your whole day in advance and the app guides you live, stop by stop, once you set off.