Constants & Units · constant

Planck constant

h = 6.626 070 15 × 10⁻³⁴ J s

Unit

J s

Value

6.626 070 15 × 10⁻³⁴

Exact

yes

Note

Fixes the kilogram since 2019. The quantum of action — the size of the graininess in nature.

Symbol

h

Category

Defining (SI)

Numeric

6.62607015e-34

Uncertainty

exact

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From the Constants database in Notion, last edited 2026-08-15. This page is the row, rendered by the build; nothing on it is written by hand.