It depends on what you measure. By city proper, Paris (105 km²) is much smaller than London (1,572 km²) — about 7% London's size. But by metropolitan area, Greater Paris/Île-de-France (12,012 km²) is much larger than Greater London (1,572 km²) — about 7.6× bigger. Both cities have similar metropolitan populations (~12-14 million) but very different administrative boundaries.
The Short Answer
Paris and London are two of the world's most iconic cities, with deeply intertwined histories. They're often compared, but direct comparison is tricky because their administrative boundaries are drawn differently. The "city" of Paris is famously compact — just 20 arrondissements covering 105 km² with about 2.1 million people. The "Greater London" administrative area covers 1,572 km² with about 9 million people. By those terms, London dominates.
But Paris doesn't end at its 20 arrondissements. The Île-de-France region surrounding Paris includes the petite couronne (inner suburbs) and grande couronne (outer suburbs). The full metropolitan area is about 12,012 km² with about 12.4 million people. So Greater Paris is larger than Greater London by area, similar in population, and very different in administrative structure.
The Real Numbers
By City Proper
- Paris (20 arrondissements): 105 km² (40.5 sq mi)
- Greater London (32 boroughs + City of London): 1,572 km² (607 sq mi)
- Ratio: London is about 15× the size of Paris proper
By Metropolitan Area
- Île-de-France (Greater Paris): 12,012 km² (4,638 sq mi)
- Greater London: 1,572 km² (607 sq mi)
- London commuter belt (full metro): ~8,400 km² (3,244 sq mi)
- Ratio: Île-de-France is about 7.6× the size of Greater London
By Population
- Paris (city proper): ~2.1 million
- Greater London: ~9.0 million
- Île-de-France: ~12.4 million
- London metro (CSA-equivalent): ~14 million
So depending on what you measure: London is bigger by city proper. Paris is bigger by metropolitan administrative area. The two are roughly tied by population.
Why the Administrative Boundaries Differ
Paris's 105 km² boundary was set in 1860 by Napoleon III, when the surrounding villages were absorbed into the city. The boundary has barely changed in over 160 years — Paris proper is essentially the same size today as it was in 1860. The compact size is a deliberate feature, designed for tight urban density.
Greater London was created in 1965 by combining the County of London with parts of surrounding counties (Middlesex, Kent, Surrey, Essex, Hertfordshire). The expansion was generous, including suburban areas that don't feel like London proper. The result: Greater London's administrative boundary stretches well beyond the dense urban core.
Île-de-France was created as a region in 1976, but it follows historical boundaries dating back to the medieval French royal domain. It includes Paris plus 7 surrounding départements (Hauts-de-Seine, Seine-Saint-Denis, Val-de-Marne, Yvelines, Essonne, Seine-et-Marne, Val-d'Oise). The region is much bigger than Greater Paris's urban core — it includes large rural areas, forests, and agricultural land.
Density Comparison
- Paris (city proper) density: ~20,000 people per km² — one of the densest cities in Europe
- Île-de-France density: ~1,030 people per km² — sparse on average due to rural areas
- Greater London density: ~5,700 people per km²
- Inner London density: ~11,500 people per km²
Paris proper is one of the densest large cities in Europe — denser than Inner London, denser than New York City overall. The 20 arrondissements are essentially solid 5-7 story Haussmannian buildings, with very little open space. This is what makes Paris so famously walkable and connected — short distances and high foot traffic.
Inner London is also dense, with similar building heights and street patterns. But Inner London is just one part of Greater London — the suburban boroughs (Bromley, Havering, etc.) have densities much closer to suburban American levels.
The Cultural Heart of Each City
Paris's 20 arrondissements spiral outward from the Île de la Cité (the original Roman settlement and home of Notre-Dame). The 1st arrondissement contains the Louvre. The 8th has the Champs-Élysées and the Arc de Triomphe. The 7th has the Eiffel Tower. The 4th has the Marais and Île Saint-Louis. The city is small enough to walk across in 2-3 hours.
London's cultural heart is similarly concentrated but spread across more boroughs. The City of London (1.12 sq mi) is the original Roman settlement and current financial district. Westminster has Big Ben, Parliament, and Buckingham Palace. Camden, Soho, Notting Hill, and Greenwich all have distinct cultural identities. But London's sprawl means there's no equivalent to walking from the Louvre to the Eiffel Tower in 45 minutes — equivalent distances in London take longer.
Economy
Greater London's metro GDP is about $900 billion. Greater Paris/Île-de-France GDP is about $770 billion. London's metro economy is roughly 17% larger than Paris's. Both are top-tier global cities by economic output.
London is generally considered the #1 financial center in Europe (sometimes tied with NYC globally), with major banking, foreign exchange, and insurance industries. Paris is the largest financial center in the EU after London's Brexit-driven decline, and home to major multinational corporations (L'Oréal, LVMH, TotalEnergies, BNP Paribas, etc.). Both cities have significant tech sectors and major universities (Imperial, UCL, LSE, King's in London; Sorbonne, École Polytechnique, HEC in Paris).
Transit and Connectivity
Paris has one of the world's most efficient metro systems — 14 main metro lines (plus RER suburban lines) running through 308 stations across just 105 km². The Paris Metro carries about 1.5 billion passengers annually. Trains run every 2-4 minutes during peak hours.
London has the world's oldest underground system — the London Underground opened in 1863. The Tube has 11 lines, 272 stations, and carries about 1.35 billion passengers annually. London also has extensive overground and DLR networks, plus the Elizabeth Line (Crossrail), which opened in 2022 and is now one of the busiest railway lines in the UK.
Both cities have dense bus networks and major international rail connections — Paris through Gare du Nord (Eurostar to London), Gare de Lyon (TGV to southern France), etc. London has 6 major rail terminals connecting to the rest of the UK.
Climate
Paris has a maritime/continental hybrid climate. Summers are warm (24°C average) and winters are cool (4°C average). Snow is rare. Rainfall is moderate and distributed across the year.
London has a more strictly maritime climate — milder summers (22°C average), milder winters (5°C average), and famously frequent overcast skies and light rain. London experiences less temperature extremes than Paris (both hot and cold) due to its closer proximity to the Atlantic.
History
Paris was founded as the Gallo-Roman settlement of Lutetia around 250 BC, on the Île de la Cité. The Romans developed it as a regional center; by the 12th century it had become the capital of the Kingdom of France. Paris has been one of the world's most important cities continuously for at least 1,000 years.
London was founded as the Roman settlement of Londinium in 43 AD on the north bank of the Thames. After Roman withdrawal it was largely abandoned, then refounded by the Anglo-Saxons in the 7th century. By the medieval era it had become England's capital and was one of Europe's largest cities. London became the largest city in the world during the 19th century (overtaking Beijing) and held that title until New York surpassed it in the 1920s.
Key Facts
- London (Greater London) is 15× the area of Paris proper.
- Île-de-France (Greater Paris) is 7.6× the area of Greater London.
- Both metros have similar populations (~12-14 million).
- Paris proper is one of the densest large cities in Europe.
- London's metro economy is about 17% larger than Paris's metro economy.
Fun Facts
- You can walk across Paris (north to south or east to west) in about 2 hours.
- Greater London contains 13% of England's population on just 1% of its land area.
- The Paris Metro has fewer stations (308) than the NYC subway (472) but covers a smaller area more intensively.
- The Channel Tunnel connects Paris and London — Eurostar takes about 2 hours 15 minutes city center to city center.
- Both cities have famous tall observation features — the Eiffel Tower (330 m) is taller than the Shard (309 m).
The Bottom Line
By city proper, London is much bigger than Paris — 15× the area. By metropolitan area, Paris's Île-de-France is bigger than Greater London — 7.6× the area. Both have similar metropolitan populations. The difference is mostly about how the boundaries are drawn: Paris keeps its city proper tiny and counts a vast surrounding region as "Greater Paris," while London absorbed its surrounding suburbs into Greater London directly.
For everyday purposes, both cities are roughly the same scale — top-tier world capitals with about 12-14 million metro residents, comparable economies, and global cultural reach. The "is one bigger" question depends entirely on which boundary you mean.