The oceanic manta ray (Mobula birostris) is the largest ray alive, reaching about 7 meters (23 ft) from wingtip to wingtip, with anecdotal reports of animals up to 9.1 meters (30 ft). The reef manta ray (Mobula alfredi) is smaller: it tops out at about 5.5 meters (18 ft) and rarely exceeds 4 meters (13 ft), although in southern Mozambique most adults span 3 to 4.9 meters (10–16 ft). No free-swimming manta has ever been weighed, but the heaviest on record, from 1916, was put at 2,721 kilograms (6,000 lb).
This guide is written by the scientists of the Marine Megafauna Foundation, whose research described all three manta ray species and underpins their IUCN Red List assessments.
How big are manta rays?
Manta rays are measured by disc width, the straight-line distance between the tips of the two pectoral fins, and by that measure the oceanic manta reaches about 7 meters (23 ft) and the reef manta about 5.5 meters (18 ft). Those are maxima, though, and the animals you would meet in the water are usually well short of them.
The current IUCN Red List assessments set out the figures. The oceanic manta attains a maximum disc width of 700 centimeters, with anecdotal reports up to 910 centimeters, while the reef manta reaches 500 centimeters but rarely exceeds 400. The third species, the Atlantic manta ray (Mobula yarae), was only described in 2025; historical records of the Atlantic form reach over 6 meters (20 ft), but a verified maximum for the newly described species has yet to be published.
Width is the right measure because a manta’s disc is far wider than it is long. In our early doctoral research on Mozambique’s mantas, the disc of the oceanic manta was roughly 2.2 to 2.3 times as broad as it was long, so a 7-meter animal measures only about 3 meters (10 ft) from the front of its head to the rear edge of its fins. The thin, whip-like tail adds length but almost no bulk, and it is often damaged or missing, which makes total length an unreliable measurement for rays.
There are size differences between populations, too, and they explain an apparent contradiction in the numbers above. Reef mantas in Mozambique are large for their species, so “most adults are 3 to 4.9 meters across” and “rarely over 4 meters” can both be true: the first describes one well-studied population, the second the species as a whole. We return to why populations differ further down this page.
How big is an oceanic manta ray?
In the populations measured so far, most adult oceanic mantas span 4 to 6 meters (13–20 ft); animals over 6 meters are genuinely rare, and the 7-meter maximum is the far edge of the range. It is the largest of the three manta species and, by width, the largest ray of any kind.
A global compilation of size records for ocean giants, which we co-authored, found that the largest oceanic manta in its dataset measured 6.2 meters (20 ft) across, against the accepted maximum of at least 7 meters. Our own surveys in southern Mozambique tell a similar story. Every oceanic manta we sized there was over 4 meters across, most were between 5.0 and 5.9 meters (77%), and only two individuals, both females, exceeded 6 meters. The largest animals our team estimated in the water, in Mozambique and Mexico, were slightly over 6 meters (20 ft).
Measured specimens are smaller still, because the animals that can be laid out and taped are mostly those killed in fisheries or bather-protection nets. The largest oceanic manta specimen examined in that doctoral research, from the fishery at Tanjung Luar on Lombok in Indonesia, measured 4.7 meters (15 ft). Specimens are the animals that can be measured most exactly, yet here they fell well short of the largest rays seen alive, which is one reason the upper end of the size range is so hard to pin down. See the oceanic manta ray species page for its range and biology.
How big is a reef manta ray?
Most adult reef mantas span 3 to 4.9 meters (10–16 ft), with females larger than males; the biggest reach about 5.5 meters (18 ft). That makes the reef manta one of the largest rays in the world, even though it is the smaller of the two widespread manta species.
The most detailed size data come from southern Mozambique, where we photo-identified 449 reef mantas between 2003 and 2007. Only seven of them (1.6%) were smaller than 3 meters (10 ft), and only four (0.9%), all females, were larger than 5 meters. The sexes separated clearly: 85.7% of females fell between 4.0 and 4.9 meters, while most males (56.6%) were between 3.0 and 3.9 meters. Over five years of observations, females in the population ranged from about 2.8 to 5.5 meters (9–18 ft).
Reef mantas elsewhere run smaller. Off eastern Australia, where researchers measured 75 individuals with lasers, 62 were between 3 and 4 meters, five were smaller, and the eight above 4 meters were all females; most males were 3 to 3.5 meters across. The difference is real enough that the Red List’s species-wide statement, that reef mantas rarely exceed 4 meters, would understate a typical adult female off Mozambique. More on the reef manta ray species page.
How big is an Atlantic manta ray?
The maximum size of the Atlantic manta is not yet established: historical records of the Atlantic form reach over 6 meters (20 ft), but most modern measurements come from nursery areas, where the mantas are mainly juveniles 2 to 3 meters (7–10 ft) across. The 2009 redescription of the genus, working from limited historical material, gave the putative Atlantic manta a maximum disc width of over 6,000 millimeters (20 ft). The species was then formally separated from the oceanic manta in 2025, in a description co-authored by MMF scientists, and a verified maximum, its size at maturity, and its size at birth have yet to be published.
Most of what is known comes from nursery areas, which is why the published animals are small. In our first study of the Palm Beach County coast in Florida, 17 of 59 identified mantas (29%) were estimated at under 2 meters (7 ft), 41 (69%) at 2 to 3 meters, and only one, a female, at over 3 meters. Every male was immature. At Flower Garden Banks National Marine Sanctuary in the northwestern Gulf of Mexico, where both oceanic and Atlantic mantas occur, 95% of mantas sized over 25 years were smaller than the size at which male oceanic mantas mature, and 80% were under 3 meters. Off Fernando de Noronha in Brazil, 69% of sightings were of mantas 3 meters or smaller, and every identified male was immature.
Adults do occur: they aggregate off central Florida each spring, where our Florida Manta Project has documented courtship, and the project now measures animals directly rather than estimating their size by eye. More on the Atlantic manta ray species page.
What is the largest manta ray ever recorded?
The largest manta rays on record are oceanic mantas, but the figures differ in quality: the accepted species maximum of about 7 meters (23 ft) rests on old accounts, the largest animals measured in modern studies are a little over 6 meters (20 ft), and anecdotal reports of up to 9.1 meters (30 ft) have never been verified. Keeping those three kinds of record apart explains most of the disagreement between published sources.
The accepted maximum comes from the 2009 redescription of the genus by MMF co-founder Dr. Andrea Marshall and colleagues, which separated the reef and oceanic mantas and gave the oceanic manta a maximum disc width of over 7 meters and the reef manta about 5.5 meters (18 ft), a figure the IUCN Red List assessment rounds to 5 meters. That figure traces back to accounts from 1849 and 1953, and the 9.1-meter reports to anecdotal accounts from the late 1990s. Published sources also differ slightly at the top: a 2020 paper by Manta Trust scientists, drawing on a field guide to the family, used maxima of 6.8 meters (22 ft) for the oceanic manta and 4.5 meters (15 ft) for the reef manta.
Some of the largest historical “devil rays” turn out to have been mantas. A ray captured off Algeria and reported in 1901 at 5.2 meters (17 ft) across was long attributed to the Mediterranean’s spinetail devil ray, and a stuffed “devil ray” in the Paris museum, acquired from Spain, was later confirmed as a female oceanic manta of about 4.7 meters (15 ft). The same 2020 review concluded that the largest of these records were probably oceanic mantas that had strayed into the Mediterranean.
There is also a broader point here, made in the size review we co-authored: record-holders are rare by definition, and most individuals of a species live well below its maximum size, closer to a size that suits their environment. A 7-meter manta is to its species what a 2.2-meter person is to ours.
How much does a manta ray weigh?
Adult weights are poorly known, because no free-swimming manta has been weighed; the few figures that exist come from dead animals, and the heaviest on record was put at 2,721 kilograms (6,000 lb) in 1916. Weights for juveniles and newborns are better documented.
The heaviest figure compiled in the size review we co-authored is that early twentieth-century record: up to 2,721 kilograms, or about 2.7 metric tons. The Algerian ray of 1901, now presumed to have been an oceanic manta, was reported at 900 kilograms (2,000 lb) for a 5.2-meter (17 ft) disc. Neither animal can be re-examined, and little is known of how either was weighed, so both are best treated as indications rather than precise measurements.
Juveniles are a different matter. Reef mantas caught in bather-protection nets off KwaZulu-Natal, South Africa, measuring 2.2 to 2.5 meters (7–8 ft) across, weighed between 71 and 107 kilograms (157–236 lb) on a spring balance. A near-term fetus from Mozambique, 1.33 meters (4 ft 4 in) across, weighed 15.1 kilograms (33 lb), and a reef manta born in captivity at the Okinawa Churaumi Aquarium in Japan weighed 68.5 kilograms (151 lb) at birth, at 1.9 meters (6 ft) across.
Those figures show how quickly weight climbs with width. Between the 1.33-meter fetus and the 2.2-meter juveniles, width increases by less than double, yet weight increases almost fivefold. The one adult figure with a width attached, 900 kilograms for a 5.2-meter ray, fits that pattern, but until a measured adult manta is weighed, adult weights remain estimates.
Are female manta rays bigger than males?
Yes. In both reef and oceanic mantas, females mature at a larger size than males and grow larger overall. Females typically mature up to about a meter wider than males, and the difference shows up clearly in the size structure of any well-studied population.
In southern Mozambique, male reef mantas mature at about 3 meters (10 ft): every male with fully calcified claspers, the paired reproductive organs on the pelvic fins, measured more than 3 meters, and males began the transition at about 2.8 meters. Females were confirmed pregnant from about 3.9 meters (13 ft) and carried mating scars from 4.2 meters, so female maturity there is about 3.9 to 4 meters. Across the species’ range, the Red List gives 270 to 300 centimeters for males and 300 to 350 for females, reflecting real variation between regions.
Oceanic mantas mature larger. In Mozambique, the only sub-adult males we saw were about 4 meters (13 ft) across, suggesting males mature at around that size, and the only mature females we observed or examined exceeded 4.7 meters (15 ft); in Indonesia, fisheries data put maturity at 3.75 meters for males and 4.13 meters for females. The Red List spans 350 to 400 centimeters for males and 380 to 500 for females. The difference persists among adults: in Mozambique, 84.3% of female oceanic mantas were between 5.0 and 5.9 meters across, while 75% of males were between 4.0 and 4.9 meters.
Size alone does not settle whether a given female is mature, because pregnancy and mating scars are temporary. A 2026 study led by Dr. Madalena Cabral and co-authored by MMF’s Jessica Pate used underwater ultrasound to show that oceanic mantas can be mid-pregnancy with no visible bulge at all. For mating, pregnancy, and pupping, see our guide to manta ray reproduction.
How big is a baby manta ray?
Reef manta pups are born at about 1.3 to 1.5 meters (4–5 ft) across in the wild, roughly a third of an adult’s width; oceanic manta pups are reported at 1.2 to 2 meters (4–7 ft). By the standards of most fishes, a newborn manta is already a big animal.
The best direct measurement is the near-term fetus described by our team in 2008, taken from a pregnant reef manta speared by fishers in southern Mozambique. It measured 1,328 millimeters (4 ft 4 in) across and weighed 15.1 kilograms, had an open umbilical scar, and already carried the belly spot pattern used to identify individuals; it was described under the name Manta birostris, a year before the reef manta was recognized as a separate species, and later work identified it as a reef manta. The smallest free-swimming reef mantas we have recorded in Mozambique measured 1.5 to 1.67 meters (5 ft), and were believed to be newborns or in their first year.
Other populations agree. In the Maldives, 41 reef mantas classed as young-of-the-year among some 4,000 identified individuals ranged from 1.4 to 1.7 meters, averaging 1.6, and six reef manta births in captivity in Okinawa produced pups of 1.5 to 1.9 meters. The Red List summarizes this as 130 to 150 centimeters in the wild and 180 to 190 in captivity, and gives 122 to 200 centimeters for oceanic manta pups. Newborn mantas are about one-third of an adult’s disc width, a large investment in a single offspring. Our guide to manta ray reproduction covers pregnancy and nurseries.
How do scientists measure manta rays?
Mostly by estimating disc width underwater against a diver or a known object, and, more precisely, with paired lasers or other photographic methods; live mantas can be measured with a tape, but it is difficult and the animals respond poorly to it. Measuring a large, flexing animal in open water is difficult, so many published manta sizes are given as size classes rather than exact figures.
The simplest field method is comparison with something of known size. Divers estimate width against their own length while swimming just above or below a manta as it hovers at a cleaning station, which is why our early Mozambique studies binned animals into size classes a meter wide rather than reporting exact widths. Tape measures were tried, but mantas did not respond well to them, so the team measured from the midline to one wingtip and doubled it. In Florida, our snorkelers estimated the juveniles’ widths to the nearest foot and then grouped them into 1-meter classes, because of the known inaccuracy of eyeballed sizes.
Paired lasers improve on this. Two lasers mounted 50 centimeters (20 in) apart on a camera housing project dots that act as a scale bar in the photograph, and with the fins fully extended and the camera square-on, error in the Mozambique work did not exceed 5% of disc width. Some studies measure disc length from the photograph instead and convert it to disc width with a published equation; for a related reason, our team compared preserved specimens by disc length rather than width, because their fins had curled and their width could no longer be measured consistently.
The method matters, because errors are not random. In the Gulf of Mexico, researchers noted that direct visual estimates appear to overestimate manta sizes compared with laser measurements, which suggests that surveys based on eyeballed sizes may underestimate the proportion of juveniles. Newer tools are widening the options. Our Florida team uses drones to measure swimming speed and wingbeat frequency, and our Indonesia program now uses stereo-photogrammetry, a paired-camera rig, to measure body size from video without contact.
Size is not a reliable guide to age, however. Preliminary observations suggest that the vertebrae of some mobulid rays may not yield age data, so growth has to come from re-measuring known individuals over many years, which is exactly what photo-identification combined with lasers makes possible. Our guide to manta ray lifespan explains how age is estimated.
How do manta rays compare with devil rays, whale sharks, and other giants?
Manta rays are the largest members of their family, about twice the width of the biggest devil rays, and the oceanic manta is as wide as the largest great white sharks are long; the whale shark, though, is far larger. Mantas and devil rays together make up the mobulid rays, and the family contains the largest rays in the world.
The devil rays are considerably smaller. The spinetail devil ray (Mobula mobular), long known as the “giant devil ray”, has never been accurately measured at more than 3.5 meters (11 ft); among 274 caught off Gaza, the largest was 3.2 meters. The sicklefin devil ray (Mobula tarapacana) is comparable at about 3.4 meters, and the same review argued that the spinetail’s “giant” name should be retired because its record sizes had come from misidentified oceanic mantas. At the small end, the shortfin devil ray (Mobula kuhlii) reaches about 1.3 meters (4 ft 3 in) and Munk’s pygmy devil ray (Mobula munkiana) up to 1.12 meters (3 ft 8 in). A large oceanic manta is therefore about six times the width of the smallest of its relatives.
Against sharks, the comparison depends on which measurement you use. The size review we co-authored gives a maximum of 7 meters of disc width for the oceanic manta and 7 meters of total length for the great white shark, so the widest manta matches the longest white shark, but measured across rather than along. The same review lists the whale shark at 18.8 meters (62 ft) and the basking shark at 12.3 meters (40 ft). Both are filter feeders, as mantas are, and the whale shark is the largest fish in the ocean; see our guide to whale shark size. How a manta differs from a stingray is covered in our anatomy guide.
Why do manta rays vary in size between regions?
Probably because of differences in food supply, fishing pressure, and which life stages use a particular site, although differences in measurement methods also play a part. Size varies between populations of both manta species, and disentangling the causes is still work in progress.
For the oceanic manta, the size review we co-authored found that populations differ in both average and maximum disc width: Ecuador’s mantas skewed toward smaller animals and Mozambique’s toward larger ones. The authors suggested that the differences may be directly related to food availability or could be a function of human pressure on populations, and cautioned that uneven sampling and different methods could also contribute. Laser measurements dominate the Mozambique data, but the differences between regions held up in a model that accounted for measurement method. The same review suggested more generally that large size in plankton feeders reflects the need to travel between dense, scattered patches of food, and that variation in their size between regions may track ocean productivity.
Maturity sizes vary in the same way. Published estimates of size at maturity range from 2.70 to 3.90 meters for reef mantas and 3.18 to 4.48 meters for oceanic mantas, depending on sex and region. Some of this is real biology, as the contrast between Mozambique and eastern Australia shows, and some reflects the small samples behind many of the estimates.
Where you look also matters. A survey at an adult aggregation, such as the reef manta cleaning stations off Tofo, will record big animals; a survey at a nursery, such as the Florida coast or Flower Garden Banks, will record small ones. The size structure of a site is therefore a clue to what the site is for, which is one of the most practical uses of size data. Fishing may also shape size structure, because removing animals before they reach full size changes a population’s profile; the size review noted that, given current fishing pressure, individuals in many manta populations may not be near their maximum possible ages or sizes.
Why size matters for conservation
A manta’s size is tied to its slow life history, and measuring size is one of the most direct ways to tell whether a population is reproducing. Females must grow to 3 or 4 meters or more before they can breed, and they then produce a single large pup at a time, which is why mantas have one of the lowest population growth rates of any shark or ray. A population that loses its large, mature females loses the animals its recovery depends on, and recovery can take decades.
That is why the decline at Praia do Tofo, in southern Mozambique, has been so consequential. Our long-term surveys there recorded a 99% decline in reef manta sightings and 92.5% in oceanic mantas by 2023, in a population once dominated by large, mature adults. Mozambique protected manta and devil rays in national law from January 2021, and from 5 March 2026 all manta and devil rays are listed on Appendix I of CITES, the strongest level of international trade protection.
Size data now help guide where that protection goes. Finding juveniles in Florida’s shallow coastal waters identified potential nursery habitat that management can focus on, and our Indonesia team now measures females to follow their reproductive cycle directly. Our guide to manta ray threats covers the protections in full.
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