Friday, Jul 24, 2026 The claims desk. Receipts included. POWERED BY LENZ ↗
IsThis

SCIENCE

The Claim

Pure water boils at 100 degrees Celsius at sea level (standard atmospheric pressure).

Verified by Lenz ·

The Short Version

Authoritative reference sources support this statement as the standard boiling point of pure water at sea-level pressure. The exact thermodynamic value at 1 atm is slightly below 100.00 °C, but 100 °C is the accepted rounded value in general science and education. Differences involving 1 bar versus 1 atm are technical convention issues, not a practical refutation of the claim.

Caveats

  • The exact boiling point at 1 atm is slightly under 100.00 °C, so the claim is accurate as a standard rounded value rather than an exact laboratory constant.
  • Some technical references define a 'standard boiling point' at 1 bar instead of 1 atm; for water, that yields about 99.61 °C.
  • Real boiling temperature varies with actual pressure, so altitude and weather can shift it away from 100 °C even near sea level.

The Receipts

  1. Water - the NIST WebBook

    NIST Chemistry WebBook

  2. Vapor pressure equation for water in the range 0 to 100 deg C

    NIST

  3. Water, boiling point at 101 325 Pa

    National Institute of Standards and Technology (NIST)

  4. Boiling

    Purdue University

  5. standard boiling point

    IUPAC Gold Book

  6. Water Science School: Water Temperature

    U.S. Geological Survey

  7. Water (data page) – Thermophysical properties

    NIST Chemistry WebBook

  8. Earth Fact Sheet

    NASA

  9. Does taper water boil at all temperatures?

    SciELO Mexico

  10. Boiling Point and Atmospheric Pressure - Theory pages

    Labster

+ 8 more sources — see the full list on Lenz

Filed Under

water

More Fact Checks