The Australian Health Star Rating system is a government initiative to label foods with 0.5 to 5 stars to indicate how healthy they are. The calculation is very convoluted so I created a web app to calculate it from nutritional information. As each section of the form is filled out, it also shows the relevant section of the official guide so you can fully understand the calculation process as well as clarify some definitions.

The Health Star Rating calculation is broken down into 7 steps:

1. Check if it’s in an automatic ratings category
2. Determine food category
3. Determine food form (not relevant to calculation, I’m not sure why it’s in the official guide)
4. Calculate baseline points from nutritional information
5. Calculate modifying points from ingredients
6. Calculate final score by subtract modifying points from baseline points
7. Use lookup table for final rating

I’ve tested this on a couple of foods including ones that had surprising ratings and the calculated ratings match the official ratings as expected. An extension project could be to make an app that uses OCR to calculate health star rating of a product from a photo of its nutritional information.