Elementary charge
The elementary charge has an exact SI numerical value.
Key knowledge
The elementary charge e is exactly 1.602 176 634 × 10⁻¹⁹ C by the SI definition.
Reference values
e1.602176634e-19C
Exact value · SI definitionValues and equations
e = 1.602 176 634 × 10⁻¹⁹ C
- e
- Elementary-charge constant C
Conditions and scope
- e denotes the positive elementary-charge constant; this is not the signed charge of every particle.
- Exact defining values do not eliminate practical measurement uncertainty.
Sources · 4
References
Sources retain their recorded scope. A source link alone does not establish verification of every statement.
Bureau International des Poids et Mesures (BIPM)2 sources
- Meet the ConstantsNational Institute of Standards and Technology (NIST)Reference guide
- 国際単位系(SI)第9版 · Japanese translation, V3.01National Metrology Institute of Japan, AISTReference guide · PDF
Evidence and review
BIPM defining-constant table; NIST elementary-charge value and unit.
2026-10-10 · Exact value, symbol and coulomb unit only.
Foundational review
2026-10-10 · Fresh primary-source inspection of the complete compact record, including every statement, equation, quantity and material condition, followed by independent AI editorial review. This check does not certify all linked lessons or every passage of every cited publication.
Sources from other places
Agreement within this scope
The elementary charge magnitude has exact SI value 1.602176634×10−19 C.
Electron charge is negative; e denotes the positive magnitude.
National Metrology Institute of Japan, AIST
- 国際単位系(SI)第9版 · Japanese translation, V3.01 JapanJapaneseShared standard
2.2 Table1; 2.3.1 Ampere, pp16–17
- 国際単位系(SI)第9版 · Japanese translation, V3.01
Entry details
Permanent link to this entry ↗- Record identity
- si-elementary-charge
- Revision
- core.1
- Structured reference record
- SI