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What units are commonly used for the Hubble constant?

Kilometers per second per megaparsec.

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  1. Kilometers per second per megaparsec ✔
  2. Light-years per kilogram
  3. Watts per square meter

Why: The units say how much recession speed increases for each megaparsec of distance. They describe a rate of cosmic expansion, not a simple velocity.

Huh, didn't know that: One megaparsec is about 3.26 million light-years.

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The Hubble constant has complicated units because space is a demanding customer.
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References

Answer: Kilometers per second per megaparsec. The units say how much recession speed increases for each megaparsec of distance. They describe a rate of cosmic expansion, not a simple velocity.

  1. Hubble Glossary science.nasa.gov/mission/hubble/multimedia/hubble-glossary
    H0 appears to be between 60 and 75 kilometers per second per megaparsec.
    Checked 2026-10-10.

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