Cetane Index Calculator
How to determine the cetane index of diesel fuel? Our Cetane Index Calculator can help you to find out. For calculation, enter specific values into the calculator to find the cetane index of your fuel quickly.
What is the Cetane Index?
The Cetane Index is a measure of the combustion quality of diesel fuel. It estimates how quickly the fuel will ignite in the engine, which affects performance and emissions. A higher cetane index means better combustion efficiency.
How to Use the Cetane Index Calculator
To use the calculator is simple. Enter the following values into the input fields:
 Specific Gravity at 60°F (SG)
 Aniline Point in °F (A)
For a more advanced calculation, you can also input:
 Viscosity at 40°C (cSt)
Example Input Values
1. Basic Calculator:

 Specific Gravity (SG): 0.85
 Aniline Point (A): 120°F
2. Advanced Calculator:

 Specific Gravity (SG): 0.85
 Aniline Point (A): 120°F
 Viscosity at 40°C: 2.5 cSt
How to Calculate the Cetane Index
The formula to calculate the Cetane Index (CI) is:
$\text{CI} = (454.54 – 1640.6 \times \text{SG}) + (774.74 \times \text{A}) – 0.554$
Variables:
Variable  Description 

CI  Cetane Index 
SG  Specific Gravity at 60°F 
A  Aniline Point in °F 
Calculation
1. Identify Values:

 Specific Gravity (SG): 0.85
 Aniline Point (A): 120°F
2. Apply the Formula:
$\text{CI} = (454.54 – 1640.6 \times 0.85) + (774.74 \times 120) – 0.55$$$$$
3. Calculate Intermediate Steps:
$1640.6 \times 0.85 = 1394.51$
$774.74 \times 120 = 92968.8$
4. Complete the Calculation:
$$\text{CI}=(454.541394.51)+92968.80.554=$$
$\text{CI} = (454.54 – 1394.51) + 92968.8 – 0.554 = 939.97 + 92968.8 – 0.554 = 92028.27$
Inputs Examples
1. Basic
Input Values  Calculation 

Specific Gravity (SG): 0.85  $CI = (454.54 – 1394.51) + 92968.8 – 0.554$

Aniline Point (A): 120°F  $CI = 92028.276$

2. Advanced
Input Values  Calculation 

Specific Gravity (SG): 0.85  $CI = (454.54 – 1394.51) + 92968.8 – 0.554$

Aniline Point (A): 120°F  
Viscosity at 40°C: 2.5 cSt 
FAQs
What is the Cetane Index?
The Cetane Index indicates the ignition quality of diesel fuel and how quickly it will ignite in an engine.
Why is the Cetane Index important?
A higher Cetane Index indicates better combustion efficiency, which will improve the engine’s performance at a lower emission level.
Can I use this calculator for all kinds of diesel fuel?
Yes, the purpose of this calculator is to estimate the cetane index of various diesel fuel types.
Conclude
How did you find our Cetane Index Calculator? I hope it was helpful and easy to use. Please share your experience and feedback. Your input helps us improve our tools for better user experience.