Clean Shipping Index ranks ships on
their environmental performance

It’s quite an intricate system, but here is our method in a nutshell
The basis of the Clean Shipping Index is a questionnaire covering the environmental performance of ships. The questionnaire is accessible for all shipowners and does not require membership in Clean Shipping Index. The questions cover general information about the shipping company as well as vessel-specific information. A key point is that this process goes beyond existing regulations and covers vessels of all types.

Vessels are scored on the following parameters


  • Harmful for the human respiratory system
  • Contributes to particulate matter (PM) pollution
  • Acidic precipitation affects vegetation and freshwater bodies


  • Leads to smog and tropospheric ozone formation
  • harmful for the human respiratory system
  • Acidic precipitation affects vegetation and freshwater bodies


  • Most significant greenhouse gas
  • Leads to global warming
  • Caused by burning of fossil fuels


  • Environmental toxicity
  • Bioaccumulation in marine organisms

water & waste

  • Operational discharges pollute the marine environment

particulate matter

  • Harmful for the human respiratory system
  • Ultra-fine particles can enter the cardiovascular system

The results
Final scores for vessels are based on the outcome of the questionnaire. A total of 150 points can be obtained, 30 points for each of the 5 different parameters. According to the final score, vessels are given a rating from 1 to 5 stars according to this scheme:

  • CSI Class 5: 125-150 points
  • CSI Class 4: 100-124 points
  • CSI Class 3: 75-99 points
  • CSI Class 2: 38-74 points
  • CSI Class 1: 0-37 points

The carrier’s score is based on the total score of all the carrier’s vessels.

Note that any benefits require that the self-assessed score is certified using a third party verification company. Read more about the process under Certification.

Data sharing
Ship-owners can not only see the scores of their own vessels online, but can also look at how other shipping companies are performing. Stakeholders such as cargo owners and forwarders use the database to select their sustainable shipping options.

Click here to read more about our methodology