* Year group: SATS are taken at different ages (typically Year 2, Year 4, and Year 6 in England), and the difficulty and scoring differ for each.
* Subject: The scoring and grade boundaries will vary between subjects (e.g., English reading, English grammar, writing, maths, science).
* Specific test version: Even within a year group and subject, the precise questions and therefore the scoring can vary slightly from year to year.
To find the grade boundaries: You need to look at the specific marking scheme and results information provided by the relevant exam board (in England, this is usually the Standards and Testing Agency - STA) for the particular year and subject. These are usually published after the tests are taken. They will give you a conversion table showing the raw score (number of correct answers) and the corresponding scaled score, which is then mapped to a national curriculum level or a grade.
In short: there is no fixed conversion chart. You must always refer to the official documentation for the specific SATS exam in question.