API Gravity Calculator
Convert between API gravity and specific gravity for crude oil and petroleum products
Input Parameters
Enter either API gravity or specific gravity to convert
About API Gravity
API gravity is a measure of how heavy or light a petroleum liquid is compared to water. The formula was developed by the American Petroleum Institute.
- API > 10: floats on water (lighter)
- API < 10: sinks in water (heavier)
- Light crude: API > 31.1
- Medium crude: API 22.3 - 31.1
- Heavy crude: API < 22.3
Results
Enter values and click Calculate to see results
Common Petroleum Products
| Product | API Gravity | Specific Gravity |
|---|---|---|
| Light Crude Oil | 35 - 45 | 0.80 - 0.85 |
| Medium Crude | 25 - 35 | 0.85 - 0.90 |
| Heavy Crude | 10 - 25 | 0.90 - 1.00 |
| Gasoline | 55 - 70 | 0.70 - 0.76 |
| Diesel | 30 - 40 | 0.82 - 0.88 |
| Fuel Oil | 10 - 20 | 0.93 - 1.00 |
Formula Reference
API Gravity to Specific Gravity
SG = 141.5 / (API + 131.5)
Where SG is the specific gravity at 60/60F (relative density to water at 60F)
Specific Gravity to API Gravity
API = (141.5 / SG) - 131.5
Density Conversions
Density (lb/gal) = SG x 8.3454
Density (kg/m3) = SG x 999.016
Density (lb/ft3) = SG x 62.428
Standards Reference
These calculations conform to:
- API 2540 - Petroleum Measurement Tables
- ASTM D1250 - Standard Guide for Petroleum Measurement Tables
- IP 200 - Petroleum Measurement Tables (UK)