Progress 8 measures a student's progress between Key Stage 2 and Key Stage 4 across eight key subjects.
It shows whether students have performed to expectation, based on a value-added measure using Key Stage 2 English and Maths as a baseline. It's checked by getting a sample of Year 11 students to sit English and Maths reference tests in March before their June GCSEs.
Progress 8 only compares schools with similar intakes.
This new measure is designed to encourage schools to offer a broad, well-balanced curriculum and will be used towards determining the 'floor standard' for schools.
See our video below (video transcript)
Calculating Progress 8
For each student, subtract their actual Attainment 8 score from their expected Attainment 8 score. This is their Progress 8.
A positive score means they made better progress than expected.
The school's Progress 8 score is the average of all students' Progress 8. A score of below -0.5 triggers an inspection, and a score of +1 or more makes the school exempt from routine inspections for a year.
See DfE's Progress 8 document for more detail and examples.