High　efficiency　video　coding　is　the　most　widely　used　video　coding　standard.　It　has　higher　coding　performance　compared　with　its　predecessor,　H.264,　but　it　also　has　higher　computational　complexity.　Interprediction　is　the　most　computationally　intensive　part　of　the　entire　video　encoding　process.　Selecting　the　optimal　interprediction　mode　by　the　rate-distortion　cost　calculation　function　requires　substantial　complex　calculation　and　memory　access,　thus　greatly　increasing　the　difficulty　of　real-time　hardware　encoding.　This　study　proposes　to　replace　the　traditional　complex　error　square　sum　calculation　with　an　estimation　method　for　distortion　and　rate.　The　estimation　of　distortion　uses　the　Hadamard-transformed　sum　of　absolute　transformation　difference　instead　of　the　complex　calculation　of　the　sum　of　squared　difference,　whereas　the　estimation　of　rate　is　obtained　by　weighting　the　number　of　prediction　units　(PUs).　The　experiment　proves　that　the　proposed　interprediction　rate-distortion　cost　calculation　model　can　greatly　reduce　computational　complexity　when　BD-rate　is　increased　by　3.02%.　In　hardware　implementation,　the　value　of　rate　can　be　obtained　by　indexing　the　number　of　PUs,　and　the　resource　expenditure　is　small.