Bi-directional Optical Flow (BDOF), is a very effective tool, developed based on the optical flow concept, which assumes that the motion of an object is smooth and is in a straight line in a short period of time. BDOF as a prediction adjustment tool for each sample, is included in VVC SW, where it derives parameters for each 4×4 block and adjusts each of its samples individually. The reference SW which is being developed for beyond VVC activity, i.e. ECM, has 2 BDOFs: One as Motion Vector (MV) refinement tool for each 8 × 8 subblock, and another one as sample adjustment BDOF similar to VVC one, but deriving the parameters for each sample. In this paper, a High-Precision BDOF is introduced which consists of the following parts: Firstly, a more accurate BDOF formula is used to derive the parameters for BDOF MV refinement. Next, a position-dependent weight is used to increase the focus of the parameter derivation. Finally, higher granularity as small as 4×4 is used for each subblock. For BDOF sample adjustment, another position-dependent weighted sum is used. The proposed method is implemented on top of ECM-7.0. Experimental results show that the proposed method provides up to –0.92% bitrate saving for some sequences compared to the latest ECM SW under random access configuration. The method explained in this paper is adopted into ECM-9.0.