Total Jitter (TJ) at a low probability level can be measured directly only on a Bit Error Ratio Tester (BERT). Many engineers however resort to TJ techniques that are not BERT based, mainly because of the prohibitively long measurement times required for a brute-force high resolution BERT scan. In this paper, we describe an optimized technique based on probability and statistics theory that enables accurate TJ measurements at the 1e-12 bit error ratio level in about twenty minutes at 10 Gbit/s.