The standard weight of a weightlifting barbell is typically 45 pounds (20.4 kg) for a men's Olympic bar and 33 pounds (15 kg) for a women's Olympic bar. However, there are also lighter bars available for beginners or specific exercises.
As for single dumbbells, they can vary widely in weight, commonly ranging from 1 pound (0.45 kg) to 100 pounds (45 kg) or more, depending on the type and purpose (e.g., light hand weights for rehabilitation versus heavy free weights for strength training).