Enter the API into the Density From API Calculator. The calculator will evaluate and display the Density From API. 

API to Density Calculator

Enter one value to calculate the other

Density From API Formula

The following formula is used to calculate the Density From API. 

D = 141.5/(API+131.5) * 998.9
  • Where D is the Density From API (kg/m^3)
  • API is the API 
API to Density Conversion Table (at 60°F)
API (°API) Density (kg/m³) Density (lb/ft³) Density (g/cm³)
81013.22163.2531.013
10998.90062.3590.999
12984.97561.4900.985
15964.78360.2300.965
18945.44959.0230.945
20932.96358.2430.933
22.3919.02857.3730.919
25903.13556.3810.903
28886.17455.3220.886
30875.19654.6370.875
31.1869.21454.2630.869
32864.50653.9690.865
35848.91552.9960.849
37838.83952.3670.839
40824.26751.4570.824
42814.66550.8580.815
45800.52849.9750.801
50778.81248.6200.779
55757.96547.3180.758
60737.82746.0610.738
* Rounded to 3 decimals. Formula used: ρ (kg/m³) = 141.5 / (API + 131.5) × 998.9 (at 60°F). Unit conversions: 1 lb/ft³ = 16.0185 kg/m³; 1 g/cm³ = 1000 kg/m³.

How to Calculate Density From API?

The following example problems outline how to calculate Density From API.

Example Problem #1:

  1. First, determine the API.
    1. The API is given as: 55.
  2. Finally, calculate the Density From API using the equation above: 

D = 141.5/(API+131.5) * 998.9

The values given above are inserted into the equation below:

D = 141.5/(55+131.5) * 998.9 = 757.878 (kg/m^3)


Example Problem #2: 

For this problem, the variables needed are provided below:

API = 65

This example problem is a test of your knowledge on the subject. Use the calculator above to check your answer. 

D = 141.5/(API+131.5) * 998.9 = ?