Scale Explorer

Space

How big is Mercury?

Mercury · Innermost planet of the Solar System

Equatorial diameter
4,879 km 3,032 mi
Equatorial radius
2,440.5 km 1,516.5 mi
Polar radius
2,438.3 km 1,515.1 mi
Mean radius
2,439.7 km 1,516 mi
Show
Human, Moon, Mercury, Mars drawn to the same scaleHuman: height 1.61–1.75 m (too small to see at this scale). Moon: diameter 3,475 km. Mercury: equatorial diameter 4,879 km. Mars: equatorial diameter 6,792 km.Human: 1.61–1.75 m (too small to see at this scale)Moon: 3,475 kmMercury: 4,879 kmMars: 6,792 kmMars6,792 kmMercury4,879 kmMoon3,475 kmHuman1.61–1.75 m · too small to see

Human is too small to see at this scale and is marked with ▲.

Everything is drawn to the same scale, standing on the same ground line. Silhouettes are simplified outlines scaled to the measured dimension. A faded outline shows the top of a size range.

Compare Mercury with something else →

Zoom out from an average adult to Mercury

Mercury is too big to show next to an average adult in one picture, so here it is in 7 steps. Each step is drawn to its own scale and zooms out from the step before.

  1. Step 1 of 7 Human → Megalodon

    A megalodon is about 8.6–15 times as long as an average adult is tall.

    Human, Megalodon drawn to the same scaleHuman: height 1.61–1.75 m. Megalodon: maximum length (estimates) 15–24.3 m.Human: 1.61–1.75 mMegalodon: 15–24.3 mMegalodon15–24.3 mHuman1.61–1.75 m
    Step 1: Human and Megalodon at the same scale.

  2. Step 2 of 7 Megalodon → Great Pyramid of Giza

    The Great Pyramid of Giza is about 5.6–9.1 times as tall as a megalodon is long.

    Megalodon, Great Pyramid of Giza drawn to the same scaleMegalodon: maximum length (estimates) 15–24.3 m. Great Pyramid of Giza: current height ≈ 137 m.Megalodon: 15–24.3 mGreat Pyramid of Giza: ≈ 137 mGreat Pyramid of Giza≈ 137 mMegalodon15–24.3 m
    Step 2: Megalodon and Great Pyramid of Giza at the same scale.

  3. Step 3 of 7 Great Pyramid of Giza → Golden Gate Bridge

    The Golden Gate Bridge is about 20 times as long as the Great Pyramid of Giza is tall.

    Great Pyramid of Giza, Golden Gate Bridge drawn to the same scaleGreat Pyramid of Giza: current height ≈ 137 m. Golden Gate Bridge: total length 2,737 m.Great Pyramid of Giza: ≈ 137 mGolden Gate Bridge: 2,737 mGolden Gate Bridge2,737 mGreat Pyramid of Giza≈ 137 m
    Step 3: Great Pyramid of Giza and Golden Gate Bridge at the same scale.

  4. Step 4 of 7 Golden Gate Bridge → Mount Everest

    Mount Everest is about 3.2 times as tall as the Golden Gate Bridge is long.

    Golden Gate Bridge, Mount Everest drawn to the same scaleGolden Gate Bridge: total length 2,737 m. Mount Everest: height above sea level 8,848.86 m.Golden Gate Bridge: 2,737 mMount Everest: 8,848.86 mMount Everest8,848.86 mGolden Gate Bridge2,737 m
    Step 4: Golden Gate Bridge and Mount Everest at the same scale.

  5. Step 5 of 7 Mount Everest → Mauna Kea

    Mauna Kea is about 1.2 times as tall as Mount Everest.

    Mount Everest, Mauna Kea drawn to the same scaleMount Everest: height above sea level 8,848.86 m. Mauna Kea: height from ocean floor to summit ≈ 10,211 m.Mount Everest: 8,848.86 mMauna Kea: ≈ 10,211 mMauna Kea≈ 10,211 mMount Everest8,848.86 m
    Step 5: Mount Everest and Mauna Kea at the same scale.

  6. Step 6 of 7 Mauna Kea → Olympus Mons

    Olympus Mons is about 2.2–2.6 times as high as Mauna Kea is tall.

    Mauna Kea, Olympus Mons drawn to the same scaleMauna Kea: height from ocean floor to summit ≈ 10,211 m. Olympus Mons: height 22–27 km.Mauna Kea: ≈ 10,211 mOlympus Mons: 22–27 kmOlympus Mons22–27 kmMauna Kea≈ 10,211 m
    Step 6: Mauna Kea and Olympus Mons at the same scale.

  7. Step 7 of 7 Olympus Mons → Mercury

    Mercury is about 180–220 times as wide as Olympus Mons is high.

    Olympus Mons, Mercury drawn to the same scaleOlympus Mons: height 22–27 km. Mercury: equatorial diameter 4,879 km.Olympus Mons: 22–27 kmMercury: 4,879 kmMercury4,879 kmOlympus Mons22–27 km
    Step 7: Olympus Mons and Mercury at the same scale.

Dimensions

MeasurementMetricImperialNotesSource
Equatorial diameter 4,879 km 3,032 mi Diameter at the equator, from NASA's Planetary Fact Sheet [2]
Equatorial radius 2,440.5 km 1,516.5 mi Radius at the equator [1]
Polar radius 2,438.3 km 1,515.1 mi Radius from the centre to a pole [1]
Mean radius 2,439.7 km 1,516 mi Volumetric mean radius (mean diameter is twice this) [1]
Mass 3.3009999999999997 × 10²³ kg 7.277 × 10²³ lb Total mass; source states 0.33010 × 10²⁴ kg [1]
Volume 60.83 billion km³ 14.59 billion cu mi Total volume; source states 6.083 × 10¹⁰ km³ [1]

About Mercury

Mercury is the smallest planet in the Solar System and the closest to the Sun, orbiting at an average of about 57.9 million km. NASA's Planetary Fact Sheet gives it an equatorial diameter of 4,879 km, a little over a third of Earth's, and a mass of about 3.3 × 10²³ kg. It has no moons and almost no atmosphere.

  • Mercury's mass is 0.0553 times Earth's and its volume 0.0562 times Earth's. [1]
  • Mercury takes 87.969 days to orbit the Sun, and one solar day (sunrise to sunrise) lasts 4,222.6 hours. [1]
  • Mercury has no natural satellites, and its surface pressure is less than about 5 × 10⁻¹⁵ bar. [1]
  • Mercury's mean density is 5,429 kg/m³, close to Earth's 5,513 kg/m³. [1]

How many fit?

  • ≈ 2.9 million × Human · height lined up end to end match the Mercury · equatorial diameter
  • ≈ 3.9 × 10²¹ × Human · body mass on the scales weigh as much as Mercury · mass
  • ≈ 1.4 × Moon · diameter lined up end to end match the Mercury · equatorial diameter
  • ≈ 4.5 × Moon · mass on the scales weigh as much as Mercury · mass
  • ≈ 2.8 × Moon · volume packed inside, by volume fill Mercury · volume

Counts divide one sourced figure by another. "End to end" uses each object's main measurement; weight and volume rows appear only when both figures are sourced.

How it compares

Factors compare the equatorial diameter of Mercury with each object’s own main measurement (height for a human). Where a size varies, the factor is given as a range.

Notes on these figures

  • The headline diameter (4,879 km) comes from the summary Planetary Fact Sheet; twice the equatorial radius on the Mercury Fact Sheet gives 4,881 km.
  • Mercury is very nearly a sphere; its polar radius is only about 2 km less than its equatorial radius.

Sources

  1. NASA Space Science Data Coordinated Archive, Mercury Fact Sheet. Accessed 25 September 2026.
  2. NASA Space Science Data Coordinated Archive, Planetary Fact Sheet - Metric. Accessed 25 September 2026.

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