How Big Can a Blue Whale Get?

They can reach 30m (100 ft) / 150-200 tons. Size varies by sex, with males typically larger than females in most species.

Quick Facts

Attribute	Details
Type	Marine mammal
Family	Cetacea
Habitat	Oceans worldwide
Conservation	Protected in most countries
Research Status	Ongoing scientific study

Blue Whale Size Records

Measurement	Record	Typical Adult
Maximum length	33.6m (110 ft)	24-30m (79-100 ft)
Maximum weight	~200 tons	100-150 tons
Largest confirmed	Female, South Georgia, 1909	—
Longest male	~30m (98 ft)	24-27m (79-89 ft)

Females are typically larger than males—an unusual trait among mammals called reverse sexual dimorphism.

Size by Body Part

Body Part	Size	Comparison
Heart	400 lbs (180 kg)	Size of a small car
Tongue	2.7 tons (5,400 lbs)	Weight of an African elephant
Mouth	Holds 90 tons of water	Could fit 100 people
Arteries	Wide enough for human to crawl through	Basketball-sized
Fluke (tail)	7.6m (25 ft) wide	Wingspan of small plane
Eye	Size of a grapefruit	15 cm (6 inches) diameter
Brain	6.9 kg (15 lbs)	One of largest of any animal

Comparison with Other Giants

Largest Animals Ever

Animal	Length	Weight	Era
Blue whale	30m (100 ft)	200 tons	Present
Argentinosaurus (dinosaur)	30-35m	70-80 tons	Cretaceous
Patagotitan (dinosaur)	31m	69 tons	Cretaceous
Fin whale	27m (89 ft)	80 tons	Present
Sperm whale	20m (67 ft)	57 tons	Present

Blue whales are 2-3 times heavier than the largest dinosaurs ever discovered.

Size Comparison Chart

Object/Animal	Compared to Blue Whale
School bus	Blue whale = 3 buses long
Boeing 737	Blue whale slightly shorter
Statue of Liberty (to torch)	Blue whale = 2/3 the height
African elephant	Blue whale = 25-30 elephants
Human	Blue whale = 2,500+ humans by weight

Blue Whale Growth

From Birth to Adulthood

Life Stage	Length	Weight	Age
Newborn calf	7-8m (23-26 ft)	2.5-4 tons	Birth
Weaning	15-16m (49-52 ft)	23 tons	6-8 months
Juvenile	20m (66 ft)	50 tons	2-5 years
Sexual maturity	22-24m (72-79 ft)	75-100 tons	5-15 years
Full adult	24-30m (79-100 ft)	100-200 tons	15+ years

Fastest Growing Animal

Blue whale calves are the fastest-growing animals on Earth:

Growth Metric	Value
Birth weight	2.5-4 tons
Daily weight gain	90 kg (200 lbs)
Daily milk consumption	380-570 liters (100-150 gallons)
Milk fat content	35-50% (vs. 4% cow milk)
Weight at weaning	23 tons
Size increase (birth to weaning)	7x heavier in 6-8 months

Why Are Blue Whales So Big?

Ocean Advantages

Factor	How It Enables Size
Buoyancy	Water supports massive body weight
No gravity limits	Land animals limited by skeletal strength
Abundant food	Krill swarms provide enormous calories
Efficient feeding	Filter feeding captures tons of food at once
Constant temperature	Ocean buffers metabolic needs

Evolutionary Path

Blue whales evolved to their current size relatively recently (in evolutionary terms):

Period	Size Trend	Cause
35 million years ago	Whale ancestors small	Transition from land
10 million years ago	Moderate size	Diversifying into new ecological niches
4.5 million years ago	Rapid size increase	Ice ages created krill abundance
Present	Maximum size	Optimal for current oceans

Blue Whale Subspecies by Size

Subspecies	Location	Average Length	Status
Antarctic blue	Southern Ocean	30m (100 ft)	Largest subspecies
Northern blue	North Atlantic/Pacific	27m (89 ft)	Slightly smaller
Pygmy blue	Indian Ocean, South Pacific	24m (79 ft)	Smallest subspecies

Even “pygmy” blue whales are still among the largest animals on Earth.

The Blue Whale Heart

The blue whale’s heart is legendary:

Heart Fact	Detail
Weight	400 lbs (180 kg)
Size	Size of a small car or golf cart
Heartbeat	8-10 beats per minute at surface
Heartbeat when diving	As low as 2 beats per minute
Blood pumped	220 liters per beat
Aorta diameter	23 cm (9 inches)

A child could crawl through a blue whale’s major arteries.

Frequently Asked Questions

Is a blue whale bigger than a megalodon?

Yes. Blue whales are larger than megalodon sharks were. Megalodon reached an estimated 15-18 meters (50-60 feet) and 50-70 tons. Blue whales reach 30 meters (100 feet) and 200 tons—nearly twice the length and 3-4 times the weight.

How big is a blue whale compared to a dinosaur?

Blue whales are larger than any dinosaur. The largest dinosaurs (Argentinosaurus, Patagotitan) weighed 70-80 tons. Blue whales weigh up to 200 tons—more than twice as heavy. In length, they’re comparable (30-35m), but blue whales are much more massive.

What is the largest blue whale ever recorded?

The largest blue whale reliably measured was a 33.6-meter (110 ft) female processed at a whaling station in South Georgia in 1909. This remains the largest animal ever documented.

How big is a baby blue whale?

Newborn blue whale calves are already enormous—7-8 meters (23-26 feet) long and weighing 2.5-4 tons at birth. They gain about 90 kg (200 lbs) per day while nursing and reach 15-16 meters by weaning at 6-8 months.

Why don’t blue whales get even bigger?

Scientists believe blue whales may be near the maximum size possible for a filter-feeding animal. Larger whales would struggle to find enough food to sustain their metabolism, and their lunge-feeding technique may become less efficient beyond current sizes.

Conservation Note

Despite their size, blue whales were nearly driven to extinction by commercial whaling. Today, approximately 10,000-25,000 blue whales remain worldwide—a fraction of pre-whaling populations estimated at 200,000-300,000. Conservation efforts continue to protect these magnificent giants.

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