Try WES if you need more accurate translation especially if your school followed the British system. WES considers the differences in education systems such that if you went to a system where 65% is a "B+", your 65% will be deemed an "A-" in the US multiple choice system. WES will translate your, say, B+ of 65% to mean an A- in the US (Multiple choice system). ECE just assigns GPA to whatever you get without factoring in the differences in the education systems. In short, expect a GPA of 3.0 or lower from ECE even if you had First Class Honors from your Brits system.
Educational Credential Evaluators