std::numeric_limits needs to be implemented for quantity. I think this should work: namespace std { template< typename T, typename U > class numeric_limits< boost::units::quantity<U, T> > : public numeric_limits<T> { typedef numeric_limits<T> type_limits; typedef boost::units::quantity<U, T> qty; public: static qty denorm_min() { return qty(type_limits::denorm_min() * U()); } static qty epsilon() { return qty(type_limits::epsilon() * U()); } static qty infinity() { return qty(type_limits::infinity() * U()); } static qty max() { return qty(type_limits::max() * U()); } static qty min() { return qty(type_limits::min() * U()); } static qty round_error() { return qty(type_limits::round_error() * U()); } static qty quiet_NaN() { return qty(type_limits::quiet_NaN() * U()); } static qty signalizing_NaN() { return qty(type_limits::signaling_NaN() * U()); } }; }