SMPTE is discussing high frame rates within the Ultra-High-Definition Television (UHDTV) Study Group and, in particular, conversions from high frame rates to today's integer and fractional standards. Although it seems an easy problem to upconvert and downconvert between frame rates when there is a simple multiplier, for example, between 119.88 and 59.94 Hz, in this paper, we show that adequate quality results cannot be obtained by simple frame doubling or frame dropping. We present a high-quality, low-complexity frame-rate conversion method, suitable for all high frame rate (HFR) conversions, such as 120 to 59.94 Hz or 50 to 120 Hz, thereby obviating the need to include fractional frame rates in the UHDTV standard.