Men tend to overestimate their height by an average of about a half-inch (1.41 centimeters), and women by 0.33 inches (0.84 cm), the study found. Black men slightly overestimate their weight, but all other groups underestimate, by as little as 0.09 pounds (0.04 kilograms) among white men to 3.8 pounds (1.74 kg) among black women.