Enter the specific gravity at 60°F and the aniline point in °F into the calculator to determine the Cetane Index. This calculator can also evaluate any of the variables given the others are known.

- Specific Gravity To Plato Calculator
- Specific Gravity To Volume Calculator
- Bulk Specific Gravity (GSB) Calculator

## Cetane Index Formula

The following formula is used to calculate the Cetane Index.

CI = (454.54 - 1640.6 * SG) + (774.74 * A) - (0.554)

Variables:

- CI is the Cetane Index
- SG is the specific gravity at 60°F
- A is the aniline point in °F

To calculate the Cetane Index, subtract 1640.6 times the specific gravity at 60°F from 454.54. Then, add 774.74 times the aniline point in °F. Finally, subtract 0.554 from the result.

## What is a Cetane Index?

The Cetane Index is a measure of the combustion speed of diesel fuel and compression needed for ignition. It indicates the quality of diesel fuel, with a higher index indicating better quality. The index is important for reducing knocking noise in the engine, improving fuel efficiency, and reducing harmful emissions. Diesel fuels with a higher cetane index are more desirable as they cause the fuel to ignite more quickly when injected into the combustion chamber.

## How to Calculate Cetane Index?

The following steps outline how to calculate the Cetane Index:

- First, determine the specific gravity at 60°F (SG).
- Next, determine the aniline point in °F (A).
- Next, gather the formula from above = CI = (454.54 – 1640.6 * SG) + (774.74 * A) – (0.554).
- Finally, calculate the Cetane Index.
- After inserting the variables and calculating the result, check your answer with the calculator above.

**Example Problem:**

Use the following variables as an example problem to test your knowledge.

specific gravity at 60°F (SG) = 0.85

aniline point in °F (A) = 120