Common non-SI units and exact SI conversions
Common non-SI unit names require their correct SI scale factors.
Key knowledge
The minute, hour and day correspond to 60 s, 3600 s and 86400 s. The litre is exactly 10⁻³ m³, the tonne is 1000 kg, and the electronvolt is exactly 1.602176634×10⁻¹⁹ J. These commonly used non-SI units are listed with SI conversions; inclusion gives them no special status within the SI and does not make them coherent SI units. Both l and L are allowed litre symbols.
Values and equations
1 min=60 s; 1 h=3600 s; 1 d=86400 s; 1 L=10⁻³ m³; 1 t=10³ kg; 1 eV=1.602176634×10⁻¹⁹ J
- min,h,d
- Minute, hour and fixed day duration unit symbols time units
- L,l
- Alternative litre unit symbols volume units
- t
- Tonne unit symbol mass unit
- eV
- Electronvolt unit symbol energy unit
Conditions and scope
- Here day means the fixed unit of duration, not the variable duration of a civil day or a solar rotation interval.
- The electronvolt conversion is exact because the elementary charge has an exact defining SI value.
- Use min for a minute of time; the prime symbol ′ denotes a minute of plane angle.
Fresh selected BIPM bodies were inspected by the Physics/Measurement author; both documents share the same normative source family. Historical accepted-unit wording is retained in old evidence/reviews only, not adopted as the new category. Practical realization uncertainty and civil/solar day duration are outside the exact conversions.
Sources · 3
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
- O Sistema Internacional de Unidades (SI) · 2ª edição luso-brasileiraInmetro and Instituto Português da QualidadeReference guide · PDF
Evidence and review
The SI-accepted time, volume, mass and energy units have the stated exact conversion factors.
Correct the category wording against BIPM SI Brochure version4.01 §4/Table8 and the2026-06-04 release: listed common non-SI units receive no special SI status. Exact scale factors, litre symbols, fixed-day/electronvolt conditions and equation/quantity data remain unchanged.
2026-10-10 · Independent Chemistry, Biology and Earth/Cosmos editor (AI editorial review). Source checks and independent AI editorial review of compact reference claims, equations, units, conditions and conceptual mappings. This is not human specialist certification, laboratory accreditation, whole-book verification, or a claim that all possible foundational knowledge is present.
Foundational review
2026-10-11 · Historical approval retained from its original dated scope: Independent AI editorial inspection of this new compact reference entry, its equations, applicability, sources and knowledge connections. Continuation 2026-10-11: foundation-measurement-accepted-unit-conversions: Correct the category wording against BIPM SI Brochure version4.01 §4/Table8 and the2026-06-04 release: listed common non-SI units receive no special SI status. Exact scale factors, litre symbols, fixed-day/electronvolt conditions and equation/quantity data remain unchanged. Unchanged claim and inventory decisions are carried forward; this delta is not a new whole-field, whole-document or human certification.
Sources from other places
Scope or convention differs
Common non-SI time, volume, mass and electronvolt units have specified SI conversions; BIPM version4.01 lists them without giving them special status within the SI.
The defined day unit has a fixed seconds conversion; civil timekeeping and coherent-SI status are separate matters. Historical Brazil2012 terminology is retained as historical conversion evidence, not a normative endorsement of the2026 status category. BIPM version4.01 §4/Table8 and the2026-06-04 release support the corrected category. foundation-measurement-accepted-unit-conversions: Correct the category wording against BIPM SI Brochure version4.01 §4/Table8 and the2026-06-04 release: listed common non-SI units receive no special SI status. Exact scale factors, litre symbols, fixed-day/electronvolt conditions and equation/quantity data remain unchanged.
Inmetro and Instituto Português da Qualidade
- O Sistema Internacional de Unidades (SI) · 2ª edição luso-brasileira Brazil and PortugalPortugueseShared standard
4 Table8 and notes(d),(g), pp21–22
- O Sistema Internacional de Unidades (SI) · 2ª edição luso-brasileira
BIPM2 sources
- SI Brochure, ninth edition, version4.01 InternationalEnglishShared standard
§4/Table8 printed140–141/PDF30–31
- Updated SI Brochure clarifies the status of non-SI units InternationalEnglishShared standard
News body, paragraphs1–3
- SI Brochure, ninth edition, version4.01
Entry details
Permanent link to this entry ↗- Record identity
- foundation-measurement-accepted-unit-conversions
- Revision
- foundations-audit.1.continuation-20261011.1
- Structured reference record
- Foundational core completion