Cambridge English Qualifications are a ladder of five general English exams, each one built around a specific level of the CEFR (Common European Framework of Reference for Languages): A2 Key for A2, B1 Preliminary for B1, B2 First for B2, C1 Advanced for C1, and C2 Proficiency for the top level, C2.
Every one of these exams is scored the same way — across Reading, Writing, Listening, and Speaking papers, combined into a single Cambridge Scale Score. That scale is what makes it possible to compare performance across different exams and sessions, and it's the same underlying system this tool uses to work out a CEFR level regardless of which exam you sat.
Because the scale is continuous rather than a simple pass/fail line, a strong result on any of these exams can actually certify the CEFR level above the exam's own target level, while a weaker result still gets recognized at the level below. That's why two candidates who both "pass" the same exam can come away with certificates showing different CEFR levels.
Most learners move through this ladder one exam at a time — from A2 Key, up through B1 Preliminary and B2 First, to C1 Advanced and finally C2 Proficiency — using each result to confirm they're ready for the next step, rather than jumping levels based on guesswork.