Male and female Tundra Swans are both entirely white with black bills and legs, making them look identical. The male is typically slightly larger than the female, though this can be difficult to discern. Males may also have a more pronounced swelling on the black knob at the base of the bill during breeding season.

• Plumage: Both sexes have pure white plumage as adults.
• Bill: They have a black bill with a yellow spot at the base, in front of the eye, which helps differentiate them from Trumpeter Swans.
• Legs and Feet: Tundra Swans have black legs and feet.
• Size: Males are generally larger and heavier than females, though this can vary.
• Male Specifics: During the breeding season, the black knob at the base of the male's bill may swell and become more prominent.
• Female Specifics: Females are slightly smaller than males and do not have any distinct physical differences.