ISO 4406 oil cleanliness code reader
Type the particle counts from an oil report to get the ISO 4406 code, and see how it compares with a target for your system. The second box turns a filter beta ratio into an efficiency.
Worked example
Inputs: 12,000 particles per mL at 4 µm, 3,000 at 6 µm, 400 at 14 µm, compared with the rolling-bearing circulating oil target.
This is the live calculator output for the default values above.
How to read the code
An ISO 4406 code has three numbers, for particles of 4 µm(c) and larger, 6 µm(c) and larger and 14 µm(c) and larger. Each step up in a number means the count is about doubled. A code of 17/15/12 is a common target for rolling bearings on circulating oil. Counts must fall as the size rises, so a result where the 14 µm count is higher than the 4 µm count signals a typing error or a bad report.
Filter beta ratio
A beta ratio of β = 200 means the filter removes 99.5% of particles of the stated size in one pass. The rule is efficiency = 1 − 1/β, so β = 75 is about 98.7% and β = 1000 about 99.9%.
Related tools and guides
Questions
What is an ISO 4406 code?
It is a three-number code that describes how many particles of 4, 6 and 14 micron and larger are in a millilitre of oil. Lower numbers mean cleaner oil.
What is a good ISO cleanliness code for bearings?
For rolling bearings on circulating oil, 17/15/12 is a common working target, but follow your bearing or machine maker for critical equipment.
What does beta 200 mean for a filter?
Beta 200 means 1 particle in 200 passes through at the stated size, which is 99.5% efficiency.
Results are starting points from standard engineering practice. Confirm critical selections with the bearing or lubricant maker.