Goliath frog: how big is the biggest frog, really?

At one end of the frog scale sits a rainforest animal that can reach about 30 centimeters (a foot) long and weigh about 3 kilograms (roughly 7 pounds). At the other end sits a frog that averages 7.7 millimeters, so small that two of them lined up end to end would still fit across a US dime. The first is the goliath frog, Conraua goliath. The second is Paedophryne amauensis. Between them lies a size gap somewhere between 25 to 1 and 40 to 1, depending on which goliath you measure.

This article puts the two side by side, with the sources. It also flags where the numbers disagree, because for the goliath frog they do. And it follows a question raised by a 2019 field study in Cameroon: could the habit of building nests help explain why this frog got so big?

Meet the goliath frog

The goliath frog lives along fast rivers and waterfalls in rainforest. The Animal Diversity Web (ADW), a University of Michigan database, says it needs clean, oxygen-rich, slightly acidic water. Its range runs from southwestern Cameroon into Equatorial Guinea, according to a 2019 paper in the Journal of Natural History.

About that voice: according to the ADW, males hold their mouths open and make a long whistling noise that females follow, while the San Diego Zoo calls the species mute. Sources disagree on whether the biggest frog in the world is silent, which is a strange thing to disagree about. This article is not a guide to finding or handling goliath frogs, and they are best watched from a distance.

How big is big? The sources disagree

Here is what three sources report for adults.

Two things explain part of the spread. First, a frog’s length is usually measured as snout-vent length, from nose to the base of the legs. The zoo’s 75-centimeter figure shows how much a stretched-out frog adds. Second, we cannot tell whether each source is quoting typical adults or the biggest animals. The sources do not explain why the ADW’s upper figure of 32 centimeters sits below the 2019 paper’s 34. The zoo also says males are larger than females. So the honest summary is: adults are commonly somewhere between 20 and 30 centimeters, and the largest reach somewhat more, with the exact record depending on who measured and how.

The other end of the scale

The smallest known frog is Paedophryne amauensis. Eric Rittmeyer, Christopher Austin and a team from Louisiana State University described it in a 2012 PLoS ONE paper, as the Cornell Chronicle reports. They found it near Amau Village in Papua New Guinea’s Central Province, in moist leaf litter on the floor of tropical wet forest. It calls from inside the litter at dawn and dusk.

The paper reports a mean snout-vent length of 7.7 millimeters, with a range of 7.0 to 8.0, measured on seven male specimens. A US dime, about 18 millimeters wide, leaves it room to spare.

The record needs two caveats. First, it is a record for the sources we read, from 2012. We did not search the literature for newer finds, and records can fall. Second, the “smallest vertebrate” version of the claim is disputed. The Cornell Chronicle says male anglerfish of the species Photocorynus spiniceps reach 6.2 millimeters, though Rittmeyer argues the comparison is invalid because those males live as parasites on much larger females. For this article, only the frog title matters.

What this looks like in practice: a size ladder

Here is the gap as arithmetic, using the numbers above. The ratio is our own calculation.

• 200 mm (the low end of the zoo’s range) divided by 7.7 mm is about 26.
• 300 mm (the high end of the zoo’s range) divided by 7.7 mm is about 39.
• 320 mm (the ADW’s top figure) divided by 7.7 mm is about 42.
• 300 mm divided by an 18 mm dime is about 17 dimes in a row.

Seventeen dimes is a lot of change for one frog. Between the extremes, other frogs on this site fit like this.

Why so big? A nest-building idea

In 2019, Marvin Schäfer and colleagues reported something new about the goliath frog. On the Mpoula River in western Cameroon they identified 19 nests along a 400-meter stretch. The nests were water-filled basins, mostly about a meter across and around 9 centimeters deep, in three types: rock pools cleared of debris, riverbank washouts cleared or enlarged, and depressions dug into gravel banks. Eggs and tadpoles turned up in all types, and a nest could hold up to three distinct groups of tadpoles. Some moved stones weighed up to 2 kilograms.

The authors hypothesize that digging such a basin takes a decent-sized frog, which might explain the species’ size. They note that other large frogs also do heavy work at spawning sites, such as the African bullfrog, which digs channels. They also note a small close relative, Conraua crassipes, which builds sandy heaps, so building may be a family trait and not a giant-only one.

The evidence has limits, and the authors say so. They never saw a frog dig. Their reading rests on the cleared basins, the piled stones, and reports from four frog hunters and two farmers. A camera aimed at one nest recorded a large frog of unknown sex sitting or moving around it from about 6:36 p.m. to 5:32 a.m. The authors write that the nests are presumably guarded. The ADW and the San Diego Zoo both say the parents give no care after the eggs are fertilized, and the 2019 study complicates that picture. For a different kind of frog parent, read about Darwin’s frog. For the tadpole-to-frog sequence, see the American bullfrog.

Common mistakes and myths about size records

Mix-up: there is one size for the goliath frog. There are at least three, and the method (snout-vent or stretched out) changes the answer.

Myth: the smallest frog is the smallest animal with a backbone, full stop. The Cornell Chronicle calls it arguably the smallest vertebrate, and notes the anglerfish dispute.

Myth: the size is explained. The nest idea is a hypothesis from one river, with a close relative that builds too.

Mix-up: huge frogs are loud. The species has no vocal sac, and sources disagree on whether it whistles at all.

Mix-up: hunting is the only trade pressure. The ADW also lists export for zoos, the pet trade and frog races.

Conservation status

The goliath frog is listed as Endangered on the IUCN Red List of Threatened Species. That is the category as distributed by GBIF, the Global Biodiversity Information Facility, and we checked it on November 9, 2026. Endangered means the species is judged to face a very high risk of extinction in the wild.

The pressures named in our sources are hunting for food, habitat loss from settlement, farming, logging and soil runoff, and export for zoos, the pet trade and frog races. The 2019 team saw hunters’ fishhooks set above breeding sites, slash-and-burn clearing and pesticide spraying along the river. Down To Earth reports that a 2016 study estimated about 19,440 frogs taken in a peak season at one mountain in Cameroon, which we could not check against the study itself. Equatorial Guinea limits exports to 300 frogs a year, according to the ADW and Down To Earth, and some habitats are protected. On trend, the ADW says the IUCN listing rests on a decline of about 50 percent over three generations. We could not open the IUCN assessment itself.

Categories are reviewed and can change, and the copy GBIF distributes can trail the IUCN website by some months, which is why we print the date we checked. GBIF’s copy does not give the year of the IUCN assessment, so we do not state one.