London Underground is longer at 250 miles long to Paris Métro's titchy 133 miles. But the Métro has more lines (16 versus 11) and more stations (303) than London (270). The Paris network also carries more passengers (1.5 billion annually) and is, in fact, the second busiest metro system after Moscow.

The answer depends on whether you are measuring by total track length or the number of stations. In 2026, the London Underground (the Tube) remains significantly "bigger" in terms of total system length, stretching over 402 kilometers (250 miles) and reaching deep into the suburbs and neighboring counties like Essex and Buckinghamshire. It is designed to move people across a vast metropolitan area. In contrast, the Paris Métro is much more compact, with a total length of approximately 226 kilometers (140 miles). However, the Paris Métro is far "denser" than the London system. It boasts over 300 stations compared to London's 272, and the average distance between stations in central Paris is often less than 500 meters, meaning you are almost never more than a five-minute walk from a Métro entrance. While London covers more ground and serves as a regional rail hybrid, Paris offers unparalleled urban accessibility within the city limits. If you include the RER (regional express) lines in Paris, the system becomes much larger, but as a pure "underground" comparison, London takes the prize for distance, while Paris wins for density and station count.