How Big Can Frogs Get?

Frogs go through a long and wonderful evolution from eggs, to tadpoles, to froglets to large adult frogs and so their size greatly varies throughout their life cycle. 

Adult frogs can grow anywhere from .30 in to 16.7 in (.77 cm to 42.5cm) and generally weigh between 0.3 oz and 98 oz (.9 g to 2.8 kg). Their size depends on their life cycle stage, but also on species, climate, diet, environment, and gender. 

There are currently over 7,400 documented frog species and so there are many different frog shapes, sizes and weights to consider. Some adult frogs can be tiny, smaller than the tip of an adult human’s pinky finger. Other frogs can grow to the size of a small house cat!

Let’s have a closer look at how big frogs can get, and the factors that may influence their size including life cycle stage, species, diet, environment, climate, predators, and gender.

Average Frog Sizes Per Species

Here is a table that details the average adult frog size per species of frog based on weight and SVL.

Snout to Vent Length (SVL) is a measurement taken in herpetology and in this case, measurements are taken starting at the tip of the frog’s nose to the most posterior opening of the cloacal slit (vent). 

Frog SpeciesLength (in)Length (cm)
Beelzebufo (Extinct)16.742.5
Goliath Frog11.228.50
Cane Toad21.2253.9
African Bullfrog9.022.86
American Bullfrog6.516.50
Poison Dart Frog1.473.75
Wood Frog25.08
Gray Tree Frog1.754.45
Spring Peeper1.243.15
Paedophryne Amauensis0.300.77

Average Frog Weight Per Species

Naturally, larger frogs in SVL tend to also be heavier frogs, and smaller frogs tend to be lighter. Here are some common frog species and their sizes based on average weight for adult specimens.

Frog SpeciesWeight (oz)Weight (g)
Beelzebufo (Extinct)NANA
Goliath Frog98.762,800
Cane Toad93.472,650
African Bullfrog70.41,995
American Bullfrog11.64330
Poison Dart Frog128.3
Wood Frog.287.8
Gray Tree Frog.247
Spring Peeper.03.9
Paedophryne AmauensisNANA

Learn more about frog weight on our blog

Tree Frogs Are Generally Small

Tree Frogs and Poison Dart Frogs tend to be smaller, around .59 in (1.5 cm) and weigh about 1 oz (28.3 g), because they need to be light since their primary environment is among the trees, sticking to leaves and branches.

Small Poison Dart Frog

Dart frogs can be found in the Amazon forest. They are tiny frogs that are extremely colorful but also very poisonous. Although they do not have many predators due to their poisonous nature, they do not grow very large in size. This allows them to easily hide in trees and on leaves.

Within the world of tree frogs, Spring Peepers tend to be fairly small at only 1.24 in (3.15 cm), and .03 oz (.9 g) on average

However, there is a wide variety of tree frogs including Gray Tree Frogs that can be more or less large.

Whereas Australian Tree Frogs can grow fairly large at 4 in (10 cm). But compared to most aquatic species, Cane Toads, or American Bullfrogs, Tree Frogs tend to be fairly small.

Aquatic Frogs Are Generally Medium-Sized

Many aquatic frog species tend to be medium-sized compared to tree frogs. Most medium-sized frogs include Green Frogs, Leopard Frogs, African Dwarf Frogs, and African Clawed Frogs.

An Aquatic Frog I Found in a Marsh

However, there are exceptions to the rule, and one of the largest ones being American Bullfrogs. These frogs are the largest in North America. Other exceptions include Javan Giant Frogs, Edible Frogs, and Anatolian Water Frogs which are larger species of aquatic frogs.

Bullfrog Facts-min
Large Adult Male American Bullfrog

Large frogs eat large prey like mice, fish, birds, bats, snakes, and even small alligators. They can also eat guppies, minnows, and smaller frogs. Their weight and size allows them to have less predators and eat more of whatever crosses their paths.

Cane Toads Are Large

Cane Toads are the world’s most invasive and largest toads in size and weight with the World Record at 53.9 cm (1 ft 91/4 in) and 2.65 kg (5 lb 13 oz). Cane Toads can be found in South America, Australia, and Southern parts of the USA.

Large Adult Cane Toad

Just like American Bullfrogs, Cane Toads can eat just about anything they can fit in their mouths including smaller frogs, snakes, birds, rats, mice, moths, and even baby alligators. 

Learn more about Cane Toads on our blog

How Long Do Frogs Take to Grow to Full Size?

As a general rule, it takes frogs 2 to 4 years to become adult frogs, to reach their full size and reproduce. The exact amount of time for them to fully grow depends on the species and the climate in which they live.

Frogs go through four main stages of evolution throughout their life cycle. Once frogs reach adulthood, they generally have grown to their full size, can mate and reproduce.

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Here is a general rule as to how long it takes for frogs to grow to full size:

StageOther NameDuration
EggEmbryo1 to 3 days
TadpolePolliwog12 to 16 weeks
FrogletYoung Frog6 to 9 weeks
Adult FrogFrog2 to 4 years

Some frogs continue to grow depending on what they have to eat around them. If there is an abundance of food and few predators, frogs can grow very large very quickly and live longer than if there was more danger and less food around them.

However, there are a number of factors that influence how long it takes frog eggs to develop into full sized adults, as well as how large the frog can be. Let’s have a look at the factors that influence frog size in more detail.

Factors That Influence Frog Size

The size to which a frog can grow is influenced by a number of factors including life cycle stage, species, diet, environment, climate, predators, and gender. Female adults, of larger species, living in favourable environments with an abundance of food and few predators tend to be much larger than other frogs.

Let’s have a look at each of these factors in mode detail.

Frog Size is Influenced by Life Cycle Stage

Frogs go through metamorphosis from eggs, to tadpoles, to froglets to large adult frogs and so their size greatly varies throughout their life cycle. Before frogs become adults, they are naturally smaller than fully grown frogs.

However, there can be some differences between tadpoles themselves, as larger frog species tend to have larger tadpoles. Since tadpoles can compete for space and resources within an environment, larger tadpoles may feed on smaller ones.

Frog Size is Influenced by Species

Genetically, depending on the type of frog, their DNA has them programmed to grow to a certain size.

Like we have already discussed, Poison Dart Frogs tend to be small, whereas American Bullfrogs are comparatively very large.

Finding a Dart Frog the size of a Bullfrog would be a very strange occurrence, since genetically they do not grow that large.

Frog Size is Influenced by Diet

If there is an abundance of food where the frogs live, and few predators around, they can grow larger than usual large. Frogs in environments with an abundance of food can grow larger, quicker, and even live longer than if there was more danger and less food around them.

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Amphibians can be overweight so this is something that can happen to frogs, especially larger species. This is especially true since frogs can’t help but pick up anything that crosses their path and that is smaller than their mouth but big enough to see.

Frog Size is Influenced by Environment

How large a frog can grow is influenced by environment including climate, seasons, human activity and the predators around them. Let’s have a look at each in more detail.

Climate plays an important role in the size frogs can grow. Many of the frogs in the rainforest are actually fairly small, and they are active all year since the climate is perfect for them to thrive and fairly stable all year long. In North America, you can find a good mix of small, large and medium sized frogs that are active in the Spring and Summer, but less active in the Fall and Winter.

The Seasons in which frogs live by plays a big role in their size and weight. For example, frogs that live in Canada and the Northern States of the US will bulk up all Summer until Fall. If they calculated things right, they will be pretty large by the time it is time to hibernate for the Winter! Frogs will burrow underground and emerge much skinnier in the Spring. And the cycle begins again.

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Human activity can play a role in influencing frog size. Urbanization, pollution, and destruction of habitats can force frogs to change their mating habits, or die trying. Polluted water can genetically modify frogs, stunt their growth, or kill them. It’s very important to care for our environment and protect vulnerable species (CTNF).

If frogs are surrounded by thousands of predators and have few places to hide, it’s a recipe for disaster. Although frogs have hundreds of awesome defence mechanisms they do not always work. On the other hand, if there are none or very little predators, frogs can thrive and will eat anything that moves past them and can fit into their mouth!

Frog Size is Influenced by Gender

Gender also plays a role in the size of frogs but you may be surprised. Some male frogs are larger than females of the same species, like African Bullfrogs that can be almost twice the size of females. In many cases, female frogs are larger than males, and with reason!

Differences Between a Male and Female American Bullfrog

Due to mating by amplexus the male frog can be on the female frog’s back for quite some time. So it is naturally better for the male to be lighter and sometimes smaller than the female frog who has to carry him around during mating season.

Common Questions About Frog Size

Why are female frogs are bigger than males? Female frogs tend to be larger than male frogs because they carry the male on their back during mating in the amplexus position. Being larger makes it easier for the female to bear the male on her back during reproduction.

What is the smallest frog in the world? The smallest frog in the world is the Paedophryne Amauensis, it is .3 in (.77 cm) SNV as an adult, which is about the size of a housefly, a human pinky fingernail, or as small as a quarter of an American dime. 

What is the largest frog ever recorded? The largest frog ever recorded was the Beelzebufo which is an extinct prehistoric frog that would be almost twice the size of the living Goliath Frog at 16.7 in or 42.5 cm. 

What is the largest non-extinct species of frog? The largest living frog species on the planet is the Goliath Frog that can grow to 12.5 in (32 cm) in length and can weigh up to 7.2 lb (3.3kg). Goliath frogs can grow larger than a rabbit or a small house cat.

How much does the smallest frog weigh? The world’s smallest frog is the Paedophryne Amauensis and although it’s weight was not specified by the researchers that found it, it probably weighs less than .01 oz or .2 g. It measures .30 in or .77 cm and is about the size of a quarter of an American dime.

Sources

Amphibian Species By the Numbers

Rittmeyer, Eric N.; Allison, Allen; Gründler, Michael C.; Thompson, Derrick K.; Austin, Christopher C. “Ecological guild evolution and the discovery of the world’s smallest vertebrate“. PLoS ONE. Public Library of Science. 7 (1): e29797. doi:10.1371/journal.pone.0029797. PMC 3256195. PMID 22253785. 2012

Evans, Susan E.; Jones, Marc E. H.; David W. Krause (2008). “A giant frog with South American affinities from the Late Cretaceous of Madagascar”. Proceedings of the National Academy of Sciences of the United States of America. 105 (8): 2951–2956. Bibcode:2008PNAS..105.2951E. doi:10.1073/pnas.0707599105. PMC 2268566. PMID 18287076.

National Geographic Society. “Poison Dart Frog”. National Geographic

 Lutz, G.; Avery, J. “Bullfrog Culture”. Southern Regional Aquaculture Center. 

Sterry, Paul (1997). Complete British Wildlife Photoguide. London: HarperCollins. ISBN 0-583-33638-8.