Please find below the 2023 performance outcome for KS4 students at John Flamsteed. Further information can be found on the DfE website by following this link: DfE Performance Tables
| Performance Measures | National Average Comparisons | JFCS 2023 Outcomes |
| Progress 8 Score | -0.03 | 0.16 |
| Average Attainment 8 Score | 46.2 | 51.20 |
| % students achieving a Grade 7 or above in English and Mathematics | Data not available | 15.8% |
| % students achieving a Grade 5 or above in English and Mathematics | 45.3% | 54.1% |
| % students achieving a Grade 4 or above in English and Mathematics | 65.1% | 76.0% |
| % students achieving a Grade 4-9 in English | 74.7% | 81.9% |
| % students achieving a Grade 4-9 in Mathematics | 70.2% | 81.9% |
| English Baccalaureate (EBacc) point score | 4.05 | 4.65 |
| % students entered for the English Baccalaureate | 39% | 56% |
| % of students staying in education or employment after KS4 | 94% | 95% |
