API Gravity Calculator
Enter specific gravity (at 60°F) to get API gravity (degrees API).
How to Use This Calculator
1
Enter specific gravity at 60°F
Use lab or datasheet SG values referenced to 60°F.
2
Click Calculate
The tool applies the standard API gravity formula.
3
Read the result
Higher °API means lighter petroleum liquids.
Formula
API = (141.5 / SG) − 131.5
Where: SG is specific gravity of the oil at 60°F (water at 60°F = 1.0).
Example: For SG = 0.85, API = (141.5 / 0.85) − 131.5 ≈ 35.76 °API.
About API Gravity
API gravity indicates how heavy or light a petroleum liquid is compared to water. It helps classify crude oils and refined products.
Typical Ranges
- Light crude: API > 31.1°
- Medium crude: 22.3° – 31.1°
- Heavy crude: API < 22.3°
Frequently Asked Questions
Can API be negative?
Yes, very heavy oils with SG > 1 can yield negative API values.
Is temperature important?
Yes. API gravity is standardized at 60°F; adjust SG to this reference.
How does API relate to density?
Higher API corresponds to lower density (lighter liquids).