Quick Answer
The api gravity to density converter computes density, specific gravity from the input values you provide.
Calculator
Result Interpretation
The result shows Density in kg/m³ and Specific Gravity in (dimensionless), computed directly from the entered inputs using the formula defined for this tool.
Worked Example
Verified calculation
Given:
- api_gravity = 10
Expected Result:
- density_kg_m3 = 999.016
- specific_gravity = 1
The actual numerical result is computed by the Runtime engine using the persisted tool definition. The values shown here come from verified test cases.
Formula / Method
ρ = (141.5 / (API + 131.5)) × 999.016Converts API gravity to mass density at 60°F. The constant 999.016 kg/m³ is the density of water at the reference temperature
Variables
| Symbol | Label | Role | Description |
|---|---|---|---|
| api_gravity | API Gravity | INPUT | API Gravity |
| density_kg_m3 | Density | OUTPUT | Density |
| specific_gravity | Specific Gravity | OUTPUT | Specific Gravity |
Calculation Steps
- Enter the api gravity in °API.
- Step 1: Compute density.
- Step 2: Compute specific gravity.
- Read the density (kg/m³) from the results.
- Read the specific gravity ((dimensionless)) from the results.
Notes / Limitations
- ASSUMPTIONMeasurement temperature is 60°F (15.56°C)
- ASSUMPTIONWater density at 60°F = 999.016 kg/m³
- ASSUMPTIONAPI gravity scale is based on the Arsel formula (1921)
- LIMITATIONDoes not account for temperature correction — density is only valid at 60°F
- LIMITATIONNot applicable to non-petroleum fluids or emulsions
- LIMITATIONAccuracy depends on accuracy of input API gravity value
Frequently Asked Questions
What is API gravity and why convert it to density?
API gravity is the petroleum industry's standard scale for measuring how heavy or light a petroleum liquid is relative to water. While API gravity is used for classification and trading, density (kg/m³) is needed for engineering calculations such as pipeline hydraulics, tank volume-to-mass conversion, and custody transfer. This converter performs the exact ASTM-defined conversion
What temperature reference is used for API gravity and density?
Both API gravity and the resulting density are referenced to 60°F (15.56°C). This is the standard reference temperature defined by ASTM D4052 and API MPMS Chapter 11.1. If your measurement is at a different temperature, you must first correct to 60°F using ASTM temperature correction tables (API MPMS Chapter 11.2.4) before using this converter
What is the accuracy of this conversion?
The conversion formula is exact by definition the constants 141.5 and 131.5 are not empirical but define the API gravity scale itself. The only source of uncertainty is the accuracy of your input API gravity value. Water density at 60°F = 999.016 kg/m³ is a well-established physical constant
What API gravity range is valid?
The formula is valid for API gravity values from 0°API to 100°API. In practice: extra heavy crude is 5–10°API, heavy crude is 10–22°API, medium crude is 22–31°API, light crude is 31–45°API, and condensate is 45–70°API. Values outside 0–100°API are physically meaningless for petroleum liquids
What are the limitations of this converter?
This converter does not apply temperature corrections it only converts at the 60°F reference. It is not applicable to non-petroleum fluids, emulsions, or mixtures where API gravity has not been measured at 60°F. For custody transfer applications, always verify against the applicable contractual specification
Technical Details
- Assumption
- Measurement temperature is 60°F (15.56°C)
- Assumption
- Water density at 60°F = 999.016 kg/m³
- Assumption
- API gravity scale is based on the Arsel formula (1921)
- Limitation
- Does not account for temperature correction — density is only valid at 60°F
- Limitation
- Not applicable to non-petroleum fluids or emulsions
- Limitation
- Accuracy depends on accuracy of input API gravity value
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