Hi, There seems to be support for 16-bit floats on iOS, when using Apple's XCode clang. This seems to be a storage-only format with the only instruction set support being conversions to and from 32- and 64-bit floats. Quick test: #if __ARM_FP & 2 #warning "Have 16-bit FP" #endif void test() { __fp16 a = 1.234; static_assert(sizeof(a)==2); __fp16 b = 2.345; auto sum = a+b; static_assert(sizeof(sum)==4); } There doesn't seem to be a std::numeric_limits specialisation. I suspect that other platforms have something similar. It would be good to have a boost::float16_t typedef and a portable feature-test macro (and maybe a software fallback). As far as I can see, boost/math/cstdfloat/cstdfloat_types.hpp checks the sizes of float, double and long double, and checks for 128-bit floats provided by the compiler. Can this be extended to check for __fp16 ? (P.S. it seems that gcc also has support, see https://gcc.gnu.org/onlinedocs/gcc/Half-Precision.html ) Cheers, Phil.