Exact scale factors and controlled physical relation

Same-Temperature Viscosity Unit and Relation Worksheet

Convert units within kinematic or dynamic viscosity using exact scale factors. Density is optional: without it, the other viscosity quantity is explicitly not calculated; with it, density must describe the same fluid state at the same declared temperature. No SUS conversion, ISO VG/SAE grade or product property is built in.

Exact SI scalingη = νρDensity optional and controlledNo SUS or grade presets

Traceable input record

ID de caso / cálculo *

Fluid, sample and batch ID *

Input quantity *

Input unit *

Input value *

Measurement temperature *

Input method, instrument and result source *

Optional cross-quantity relation: leave all three density fields blank for exact within-quantity unit scaling only. To calculate the other quantity, complete all three fields from the same sample/state and temperature.

Optional density ρ

Optional density temperature

Optional density method and source

Reviewer and date *

Eight evidence and applicability gates

The quantity belongs to the identified fluid sample/batch and physical state.

Input quantity, unit, method, temperature, result ID and uncertainty are verified.

The exact within-quantity scale factors are appropriate; no grade or property equivalence is implied.

No cross-quantity result is needed, or density is measured for the same sample/state at the same temperature.

No SUS/SFS value or Saybolt conversion is required from this worksheet.

No viscosity-temperature prediction or one-point extrapolation is being performed.

The result will not be treated as an ISO VG, SAE or product-grade assignment or selection.

An accountable reviewer will retain the input and density source records with the result.

No current result

Complete the traceable record and submit explicitly.

Converted units and optional relation

Kinematic viscosity—

Kinematic viscosity (SI)—

Dynamic viscosity—

Dynamic viscosity (SI)—

Density relation stateNot evaluated

Evidence state0 / 8 complete

No conversion record

No current numerical result is available.

Exact scales, relation and dimensional boundary

1 mm²/s = 1 cSt = 10⁻⁶ m²/s

1 mPa·s = 1 cP = 10⁻³ Pa·s

η = νρ; η [mPa·s] = ν [mm²/s] × ρ [kg/m³] / 1000

Within-quantity unit scaling needs no density. The cross-quantity relation needs a density for the same composition, pressure/state and temperature. Dimensionally, (m²/s)(kg/m³) = kg/(m·s) = Pa·s. These are dimensional and physical relations, not ISO VG, SAE or product-selection formulas.

Temperature boundary: ASTM D341-20(2025) describes a limited-range viscosity-temperature relationship when kinematic viscosities at two temperatures are known. This worksheet performs no temperature prediction.

Saybolt and decision boundary: ASTM D2161-20(2025) controls official same-temperature SUS/SFS equations and describes the petroleum-industry practice as obsolete. No protected Saybolt equation is embedded. The result does not assign a grade, select a lubricant or authorize equipment operation.

Source register and permitted use

ID	Official source and lifecycle	Used for	Not used for
S1	ISO 3448:1992, Edition 2 — published, confirmed 2023; stage 90.93	Industrial-liquid-lubricant classification scope and lifecycle.	Grade values or this page’s former preset: NEEDS_LICENSED_SOURCE.
S2	ISO 3448:1992/Cor 1:1993	Official Technical Corrigendum 1 lifecycle.	No numerical effect guessed from its public title.
S3	ASTM D445-26 — active current record	η = νρ and displayed viscosity-unit identities.	No different-temperature or generic default density.
S4	ASTM D2161-20(2025) — active current record	Same-temperature SUS/SFS scope and legacy/obsolete warning.	Exact equations/tables: NEEDS_LICENSED_SOURCE; none embedded.
S5	ASTM D341-20(2025) — active current record	Two known temperature points and limited-range warning.	No one-point temperature prediction.
S6	NIST SP 811, Chapter 8 — official guidance	SI unit framing for dynamic and kinematic viscosity.	No lubricant grade or Saybolt equation.

Corrections made during review

The generic density fallback was removed

There is no 860 kg/m³ default. Density is optional for unit scaling and mandatory, traceable and same-temperature only for cross-quantity arithmetic.

Exact unit scaling was separated from η = νρ

cSt↔m²/s and cP↔Pa·s do not need density; kinematic↔dynamic calculation does.

Forward and reverse SUS equations were removed

The former rational and piecewise approximations were not verified against the complete licensed ASTM D2161 practice and its domain.

Grade, water and engine-oil presets were removed

No generic ISO VG, water or SAE product property is supplied without a controlled source and exact sample/state.

Temperature extrapolation is prohibited

One viscosity point does not define a temperature curve. The page records the measurement temperature but predicts no other temperature.

Traceability and strict locale parsing were added

Case, sample, method/result source, temperature and reviewer are required; complete point or comma decimals are accepted and mixed/partial values are rejected.

Detached and automatic state was removed

No prefilled value, auto-calculate, quick preset, clipboard, dynamic result HTML or browser persistence remains.

FAQ schema and external dependencies were removed

Oversimplified ISO VG/SUS/Walther claims, external fonts and KaTeX no longer create detached or failing content paths.