Facts & Curiosities
The Human Body in Numbers
Published September 25, 2026 • 1 Views
Bones, beats, blood, blinks and breaths. The figures that come up in quizzes, the ones usually quoted wrongly, and what they mean.
A body is a set of surprisingly quotable numbers. These are the ones worth knowing, with the common mistakes flagged.
The structure
| Measure | Number |
|---|---|
| Bones in an adult | 206 |
| Bones at birth | About 300, many of which fuse |
| Bones in each hand | 27 |
| Bones in each foot | 26 |
| Skeletal muscles | About 600 |
| Teeth, adult | 32, including wisdom teeth |
| Teeth, child | 20 milk teeth |
| Pairs of ribs | 12 |
| Vertebrae in the neck | 7 |
More than half the bones in the body are in the hands and feet — 106 of 206 between them.
The running costs
| Measure | Number |
|---|---|
| Resting heart rate | 60–100 beats a minute |
| Heartbeats in a year | Roughly 35 million |
| Breaths a day | Around 20,000 |
| Blood volume | About 5 litres |
| Blinks a day | Around 15,000 to 20,000 |
| Litres of saliva a year | Roughly 500 |
| Body temperature | About 37°C, though the average is now measured a little lower |
| Water as a share of body mass | About 60% in an adult |
The very small and very long
- Smallest bone: the stapes, about 3 mm, in the middle ear.
- Longest bone: the femur, roughly a quarter of your height.
- Longest nerve: the sciatic, from the lower back to the foot.
- Blood vessels end to end: commonly quoted as 100,000 km, which is an estimate built on estimates. Treat it as "a very long way" rather than a fact.
- Strongest muscle: depends what you mean. The masseter, in the jaw, exerts most force for its size; the gluteus maximus is the largest; the heart does the most total work.
Figures people repeat that are wrong
- "You only use 10% of your brain." Entirely false. Brain imaging shows activity throughout, and there is no idle 90%.
- "The body replaces itself every seven years." Some cells turn over in days, others in decades. The lens of the eye and most neurons of the cerebral cortex stay with you for life.
- "Fingernails keep growing after death." The skin retracts as it dehydrates, which makes nails and stubble look longer. Nothing is growing.
- "Humans have five senses." A convention from Aristotle. Balance, temperature, pain and proprioception — knowing where your limbs are without looking — are all separate senses.