# How Slow Is a Sloth? The Science Behind the World's Slowest Mammal

*Central and South America · JUN 20 2026*

> A sloth moves only about 3 metres per minute on the ground, making it the slowest mammal on Earth; its metabolism runs at roughly 40-45% of the expected rate for its size, and a single leaf can take up to about 30 days to digest.

Sloths crawl about 3 metres a minute and can spend a month digesting one leaf. Here's exactly how slow they are, in numbers, and why their slowness keeps them alive.

## What are the key takeaways from this briefing?
- Sloths move only about 3 metres per minute on the ground, the slowest of any mammal.
- Their metabolism runs at roughly 40-45% of the rate expected for their body size.
- Digesting one leaf can take up to about 30 days, and they descend to defecate only once a week.
- Slowness is camouflage: predators that hunt by movement struggle to spot a near-motionless sloth.
- In water sloths swim about three times faster than they move on land.

## How slow is a sloth, really?

Sloths are the slowest mammals on Earth, and the numbers are striking. On the ground a sloth covers only about three metres per minute, slower than most people can walk in a single second. But slowness in a sloth is not laziness; it is an exquisitely tuned response to a diet of leaves that yield very little energy. Our [sloth species guide](/wildlife-guides/sloth/) sets out the full biology, while this explainer focuses on the speed question people search for most.

### The speed, in numbers

- **Ground speed:** roughly 3 metres per minute, the slowest of any mammal.
- **Metabolism:** only about 40 to 45% of the rate expected for an animal of their size.
- **Digestion:** a single leaf can take up to around 30 days to pass through their multi-chambered, fermenting stomach.
- **Bathroom breaks:** sloths climb down to defecate only about once a week.

### Why being slow keeps sloths alive

A sloth's main predators, including harpy eagles and big cats, hunt largely by detecting motion. By barely moving, a sloth becomes extremely hard to notice, an effect reinforced by the green algae that grows in its fur and breaks up its outline against the canopy. Low movement also means low energy use, which matters enormously when your food is hard-to-digest foliage. Sloths reinforce this by running cooler body temperatures and digesting slowly, squeezing every possible calorie from each leaf.

### The exception: sloths are surprisingly fast swimmers

Slowness on land does not mean slowness everywhere. In water a sloth can move about three times faster than it crawls on land, using its long arms in a steady stroke. It can also slow its heart rate to hold its breath for a remarkably long stretch, an ability that helps it cross rivers and flooded forest in its range. So the honest answer to "how fast is a sloth" is: almost stationary on land, but a capable swimmer when it has to be.

### When slowness becomes a danger

A sloth's slow pace is perfect for the treetops but leaves it badly exposed where rainforest has been broken up by roads and power lines. Animals that come down to cross a gap can be hit by vehicles or electrocuted, and slow, trusting sloths are easy to grab for the illegal pet trade. Partner-funded shelters in countries such as Brazil and Colombia rescue and rehabilitate these animals, and you can support that work through our [donation page](/donate/) if you'd like to help.

**[Read the full Sloth wildlife guide](/wildlife-guides/sloth/)** for the facts, IUCN status and conservation context — or **[donate to WARN](/donate/)** to help fund the local partners protecting this species.

## What do people ask about this briefing?
### How fast can a sloth move?
On the ground a sloth travels only about three metres per minute, the slowest speed of any mammal. It moves a little faster up in the trees and noticeably faster in water, where it can swim around three times quicker than it crawls on land.

### Why are sloths so slow?
Sloths eat mainly leaves, which give very little energy and are slow to digest. Moving as little as possible conserves that energy, and it also makes sloths almost invisible to predators that hunt by detecting movement.

### How long does it take a sloth to digest food?
Very long: a single leaf can take up to around 30 days to pass through a sloth's multi-chambered, fermenting stomach, one of the slowest digestion rates recorded in any mammal.

## Which sources does this briefing use?
- [Smithsonian's National Zoo - Why are sloths so slow, and other sloth facts](https://nationalzoo.si.edu/animals/news/why-are-sloths-so-slow-and-other-sloth-facts)
- [Smithsonian Tropical Research Institute - Life in slow motion](https://striresearch.si.edu/rainforest/how_animals_adapt/life-in-slow-motion/)
- [Britannica - Sloth](https://www.britannica.com/animal/sloth)

Human-readable page: https://worldanimalrescuenetwork.org/newsroom/sloth-how-slow-is-a-sloth/