The orangutan is one of humanity’s closest living relatives, adapted for an arboreal life fundamentally different from our own. To understand how orangutans compare to humans in size, it is necessary to examine specific metrics, including mass, height, and limb proportions. While human height often surpasses a standing orangutan, the ape’s overall mass and sheer reach are far greater.
Key Metrics: Weight and Standing Height Comparison
A comparison of weight highlights the orangutan’s superior physical mass, especially in adult males. An average adult human male weighs approximately 90 kilograms (199 pounds) and stands about 175 centimeters (5 feet 9 inches) tall. In contrast, an adult female orangutan typically weighs 37 to 40 kilograms (82–88 pounds) and measures around 115 centimeters (3 feet 9 inches) in height.
The most significant size difference appears with the dominant adult male orangutan, which can weigh over twice as much as the female. A mature male typically weighs 75 to 90 kilograms (165–198 pounds), but larger Bornean males can exceed 120 kilograms (265 pounds). This means a dominant male orangutan can easily outweigh an average human male. While the orangutan’s standing height is generally less than a human’s, averaging about 137 centimeters (4 feet 6 inches) for males, this measurement is deceptive. Orangutans spend nearly all their time in the forest canopy, moving quadrupedally, meaning their full vertical stature is rarely expressed like that of a habitually bipedal human.
The Defining Feature: Arm Span and Reach
The defining physical difference is the disproportionate length of the orangutan’s arms, an adaptation for their arboreal lifestyle. Humans generally have an arm span roughly equal to their standing height. In contrast, the orangutan’s arms are structurally much longer than their legs, reflecting a life spent swinging and climbing through trees (brachiation).
This adaptation gives the orangutan an incredible reach. An adult male’s arm span often measures up to 2.2 meters (7.2 feet) from fingertip to fingertip, and some large males reach 2.4 meters (nearly 8 feet). This span is more than one and a half times their standing height. This immense horizontal reach allows the orangutan to navigate the forest canopy with ease. Their hands are long and hook-like, with a short thumb, perfectly suited for grasping branches rather than the fine manipulation favored by human hands.
Sexual Dimorphism in Orangutans vs. Humans
The overall size comparison is complex due to the stark difference in size between male and female orangutans, known as sexual dimorphism. Orangutans exhibit one of the most extreme levels of size difference among the great apes. Adult males can weigh more than twice as much as adult females, establishing a male-to-female body weight ratio significantly higher than in humans.
Human sexual dimorphism is relatively minor, with males typically weighing only about 15 to 28 percent more than females. The male orangutan’s size is amplified by secondary sexual characteristics that develop with maturity. These include large, fleshy cheek pads, or flanges, made of fibrous fatty tissue, which frame the face and are linked to higher testosterone levels. Dominant males also develop a large throat sac that acts as a resonating chamber, amplifying their “long calls” to attract females and establish territory. This impressive bulk and pronounced features, which are not present in females, mean that a comparison between a human and an orangutan heavily depends on the sex of the ape.