API Gravity Calculator
Calculate API gravity from density or density from API gravity for petroleum products
API Gravity Calculator
Select a common liquid or use custom density
Density of the liquid at 60°F (15.6°C)
Calculation Results
API Gravity
Specific Gravity
Crude Oil Classification
Formula used: API = (141.5 / Specific Gravity) - 131.5
Specific Gravity: SG = ρ_liquid / ρ_water (at 60°F)
Water density: 999 kg/m³ at 60°F (15.6°C)
Buoyancy Analysis
Example Calculation - Gasoline
Given Parameters
Liquid: Gasoline
Density: 750 kg/m³ at 60°F
Water density: 999 kg/m³ at 60°F
Calculation Steps
Step 1: Calculate specific gravity
SG = 750 kg/m³ ÷ 999 kg/m³ = 0.7508
Step 2: Apply API formula
API = (141.5 ÷ 0.7508) - 131.5 = 188.48 - 131.5
Result: API = 56.98° API (Light Crude)
API Gravity Classification
Common Liquid Examples
Water: 10° API (reference point)
Gasoline: ~57° API (light)
Kerosene: ~51° API (light)
Diesel: ~35° API (medium)
Heavy Oil: ~15° API (heavy)
Understanding API Gravity
What is API Gravity?
API gravity is a measure of how heavy or light a petroleum liquid is compared to water. Developed by the American Petroleum Institute (API), it's the standard measure used in the petroleum industry to classify crude oil quality and value.
Why is it Important?
- •Determines crude oil quality and market value
- •Predicts refinery yield and processing requirements
- •Indicates whether oil will float or sink in water
- •Essential for oil trading and transportation
API Gravity Formula
API = (141.5 / SG) - 131.5
- API: API gravity in degrees (° API)
- SG: Specific gravity relative to water
- 141.5, 131.5: Empirical constants
Specific Gravity Formula
SG = ρ_liquid / ρ_water
- ρ_liquid: Density of the petroleum liquid
- ρ_water: Density of water (999 kg/m³ at 60°F)
Note: All measurements are standardized at 60°F (15.6°C)
Commercial Value and Applications
High-Value Range
35-45° API (Light Crude)
Most valuable crude oil range. Produces high yields of gasoline, diesel, and other valuable light products.
Processing Considerations
Higher API = Easier Processing
Light crude oils (high API) require less complex refining processes and yield more valuable products.