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

56.98° API
American Petroleum Institute gravity

Specific Gravity

0.7508
Relative to water at 60°F
750.0 kg/m³
Kilograms per cubic meter
0.750 g/cm³
Grams per cubic centimeter
46.82 lb/ft³
Pounds per cubic foot

Crude Oil Classification

Extra Light Crude
🛢️ This liquid will float on water (lighter than water)

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

⬆️ This liquid is lighter than water and will float (API > 10° API)
⚠️ Extra light crude (> 45° API) - may be less valuable due to processing limitations

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

Extra Heavy< 15° API
Heavy Crude15-25° API
Medium Crude25-35° API
Light Crude35-45° API
Extra Light> 45° API

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.