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Eiffel Tower's Surprising Growth: Science of Thermal Expansion Revealed
Discover the science behind the Eiffel Tower's remarkable seasonal height changes, as thermal expansion causes this iconic landmark to grow and shrink with temperature.
Nikhil Wad
April 04, 2025
In partnership with
Why the Eiffel Tower Grows Taller in Summer and Shrinks in Winter
The Eiffel Tower, one of the most famous landmarks in the world, isn’t as static as it seems. During the summer months, the iron structure can grow by up to 15 centimeters (6 inches) due to a natural phenomenon known as thermal expansion. Similarly, in colder months, it contracts back to its original height.
It’s a fascinating reminder that even monumental structures are subject to the forces of nature. But how does this process work? And why does the Eiffel Tower, in particular, experience such noticeable changes?
Let’s break it down.
The Science Behind Thermal Expansion
The key reason for the Eiffel Tower’s seasonal height changes lies in thermal expansion, a fundamental principle in physics. This occurs because metal expands when heated and contracts when cooled.
Here’s how it works:
When iron is exposed to heat, the atoms inside it start moving more rapidly, causing the material to expand.
In colder temperatures, the opposite happens—the atoms slow down, and the material contracts.
For a structure as tall as the Eiffel Tower (330 meters or 1,083 feet), even a small amount of expansion per meter adds up, leading to an increase of about 15 centimeters (6 inches) in height during the peak of summer.
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Why Does the Eiffel Tower Expand So Noticeably?
Several factors make the Eiffel Tower more susceptible to expansion than other buildings:
Made Entirely of Iron
Unlike modern skyscrapers built with a mix of steel, concrete, and glass, the Eiffel Tower consists of 18,038 iron pieces, which are particularly prone to thermal expansion.Large Surface Area Exposed to Sunlight
The lattice structure of the tower means that sunlight can reach multiple sections, heating up different parts at different rates. This can even cause slight tilting!Paris’s Seasonal Temperature Swings
The temperature in Paris can vary from around -5°C (23°F) in winter to 35°C (95°F) in summer. These fluctuations lead to noticeable size changes.
Does the Expansion Affect the Tower’s Stability?
Even though the Eiffel Tower changes height throughout the year, it remains structurally sound. Gustave Eiffel, the engineer behind the tower, designed it with thermal expansion in mind.
The iron framework allows for flexibility, preventing cracks or damage from temperature changes.
Expansion joints and the tower’s design absorb movement, ensuring it remains stable even with its seasonal height shifts.
Despite growing taller, the tower’s center of gravity remains well-balanced, so there’s no risk of instability.
Interestingly, on especially hot days, the uneven heating can cause the top of the tower to tilt slightly—up to 7 inches (18 cm) away from the sun!
Did You Know?
The tallest recorded height of the Eiffel Tower due to heat expansion was in the summer of 1976 when it reached 330.3 meters (1,084 feet).
The tower was originally 312 meters (1,024 feet) when completed in 1889, but its current official height includes an antenna, making it 330 meters (1,083 feet) tall.
Engineers take thermal expansion into account when designing bridges, railways, and buildings, ensuring they can expand and contract safely.