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The 16 pages that link to 2019 redefinition of SI base units, each with the reason it gives.

• International System of UnitsBroader topic: It completed the transition away from definitions tied to material objects.

• Molar massRelated: It fixed the Avogadro constant and thereby gave the mole an exact particle count.

• Avogadro constantBroader topic: It made the Avogadro constant's stated value exact by definition.

• KilogramRelated: It replaced the prototype-based kilogram definition with one based on the Planck constant.

• MoleRelated: It replaced the mole's carbon-12-based definition with an exact Avogadro constant.

• Vacuum permittivityRelated: It ended ε₀’s exact-value status by fixing the elementary charge instead.

• Unit of measurementRelated: It replaced several artifact-based definitions with standards grounded in constants of nature.

• AmpereRelated: It replaced the ampere's force-based definition with one based on elementary charge.

• Reduced Planck constantRelated: The redefinition fixed Planck’s constant exactly, thereby fixing ℏ in SI units.

• KelvinBroader topic: It replaced the water triple point with the fixed Boltzmann constant as the kelvin's defining basis.

• Faraday constantRelated: Fixing the elementary charge and Avogadro constant makes the Faraday constant exact in SI.

• General Conference on Weights and MeasuresBroader topic: The Conference approved the shift from artifact-dependent definitions to fixed constants.

• Amount of substanceBroader topic: It made the Avogadro constant exact and thereby gave the mole its present definition.

• International Prototype of the KilogramRelated: It replaced the prototype’s role with a definition anchored to the Planck constant.

• Physical constantRelated: It changed constants such as Planck's constant from measured quantities into anchors of unit definitions.

• Ampère's force lawRelated: It replaced the force-based definition of the ampere with a fixed value for the elementary charge.