API ↔ SG Converter

API gravity is the petroleum industry's inverse-SG scale. API = 141.5/SG − 131.5 (both at 60 °F).

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This calculator requires JavaScript to compute its result. The formula, symbols, and regulatory sources are shown in the Formula section below.

Formula, assumptions, and limits

\text{API} = \frac{141.5}{SG_{60}} - 131.5

Symbol	Meaning	Unit
$SG_{60}$	Specific gravity at 60 °F
$API$	API gravity	°API

Source: API MPMS Chapter 11.1

API gravity is the petroleum industry's inverse-SG scale.