Olympus Mons is about 2½ Everest elevations tall.

Earth's tallest mountain is not the benchmark once you leave the planet. NASA describes Mars' Olympus Mons as 21.9 km tall — roughly two and a half Everests.

Comparing mountain "height" between Earth and Mars needs care. Earth has a global ocean surface that gives an intuitive sea-level reference. Mars doesn't have one.

So this is a comparison between NASA's stated Olympus Mons height and Everest's accepted elevation — not two geodetically identical measurements.

Olympus Mons height

21.9 kmSource value

NASA

Everest elevation

8.84886 kmSource value

8,848.86 m

Ratio

21.9 ÷ 8.84886 ≈ 2.47Calculated

Published

≈2.5 Everest elevationsResult

Derived comparison from authoritative reference values · planetary reference systems differ. 21.9 km is NASA's stated height; Everest is measured against Earth's sea-level-based reference. The ratio is Scaleidoscope's.

Tied to the cited NASA reference basis of about 21.9 km. That is not the only defensible definition of Olympus Mons' height.

• NASA

  Olympus Mons(opens external site)
• Reuters (news report; measured by the joint Nepal–China 2020 survey)(opens external site)

• NASA Science

  Olympus Mons(opens external site)

  Olympus Mons is 21.9 km tall

• Survey Department, Government of Nepal

  Measurement of Height of Mt. Sagarmatha (Dangol et al.)(opens external site)

  Orthometric height 8,848.86 m

• Scaleidoscope

  Scaleidoscope derived calculation from sourced official dimensions

  Scaleidoscope arithmetic from the sourced inputs

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