Postgraduate Research
To apply for a PhD (or other postgraduate research qualification) you must have an undergraduate (Bachelors) degree from a recognised American university, usually in a related subject area, with a B average or equivalent GPA or percentage mark (depending on the subject that you wish to study) which is equivalent to a UK Upper Second Class Honours degree (also known as a 2:1).
Each course page sets its IELTS band; equivalent scores per band: IELTS Academic: 5.5=5.5; 6.0=6.0; 6.5=6.5; 7.0=7.0; 7.5=7.5 | TOEFL iBT: 6.0=80; 6.5=90; 7.0=100; 7.5=110 | Pearson Test of English (PTE): 6.0=59; 6.5=61; 7.0=68; 7.5=75 | Cambridge CPE and CAE (test taken after Jan 2015): 6.0=169; 6.5=176; 7.0=185; 7.5=191 | Duolingo English Test (DET): 5.5=95; 6.0=105; 6.5=120; 7.0=130; 7.5=140