A bearded dragon is about 3 in long at hatching, 8–11 in (20–28 cm) at 3 months, 11–18 in (28–46 cm) at 6 months and 15–24 in (38–61 cm) at 1 year. Most reach full size of 15–26 in (38–66 cm) by about 18 months. After that, size can't tell you a dragon's exact age.
Estimates only. Every bearded dragon grows and ages a little differently. See a reptile vet for health concerns.
Bearded dragon size by age: how big should my dragon be?
Bearded dragons hatch at about 3 inches long and weigh just a few grams, yet within a year and a half most are 16–24 inches from nose to tail tip. That makes bearded dragon size by age one of the most useful things a new keeper can check: it shows whether a young dragon is growing on track, when to upgrade its enclosure and roughly how old a dragon of unknown age might be.
The calculator above works in both directions. In Age → size mode, enter your dragon's age in weeks, months or years to see the expected length and weight range, its life stage, how close it is to adult size and the enclosure it needs. In Length → age mode, enter its length (and weight, if you have it) to answer "how old is my bearded dragon?". Switch between inches and centimeters, or grams and ounces, at any time.
As a quick guide, a 3-month-old dragon is usually 8–11 in (20–28 cm), a 6-month-old 11–18 in (28–46 cm) and a 1-year-old 15–24 in (38–61 cm). The ranges are wide on purpose: two healthy dragons from the same clutch can differ by several inches at the same age.
Bearded dragon size chart by age
This bearded dragon size chart by age lists the typical total length and weight from hatching to adulthood. Life stages follow the vet-reviewed stages in Chewy's size guide: hatchling up to about 2–3 months, juvenile to 11 months, sub-adult from 12 to 18 months and adult after that.
| Age | Length (in) | Length (cm) | Weight (g) | Life stage |
|---|---|---|---|---|
| At hatching | 3 in | 8 cm | 4 g | Hatchling |
| 1 month | 3–4 in | 8–10 cm | 4–6 g | Hatchling |
| 2 months | 5–9 in | 13–23 cm | 8–40 g | Hatchling |
| 3 months | 8–11 in | 20–28 cm | 20–110 g | Juvenile |
| 4 months | 9–12 in | 23–30 cm | 40–115 g | Juvenile |
| 5 months | 11–16 in | 28–41 cm | 100–150 g | Juvenile |
| 6 months | 11–18 in | 28–46 cm | 180–225 g | Juvenile |
| 7 months | 13–18 in | 33–46 cm | 225–280 g | Juvenile |
| 8 months | 13–20 in | 33–51 cm | 230–325 g | Juvenile |
| 9 months | 14–21 in | 36–53 cm | 250–350 g | Juvenile |
| 10 months | 15–22 in | 38–56 cm | 260–375 g | Juvenile |
| 11 months | 15–23 in | 38–58 cm | 280–400 g | Juvenile |
| 1 year | 15–24 in | 38–61 cm | 300–450 g | Sub-adult |
| 18 months | 15–26 in | 38–66 cm | 300–550 g | Adult |
| 2 years and older | 15–26 in | 38–66 cm | 300–550 g | Adult (fully grown) |
No veterinary school publishes a month-by-month growth chart for bearded dragons, so the lengths and weights come from reptile.guide's widely used keeper chart. The hatching size (about 3 in, as little as 4 g) is from the same guide; Chewy's vet-reviewed guide gives 2–3 in at hatching. Centimeters are converted from inches and rounded.
Bearded dragon full size age: when do they stop growing?
Most bearded dragons reach their full size at about 18 months. Both reptile.guide and Chewy's vet-reviewed guide put full size at 18 months, and PetMD's lifespan article says dragons reach maturity between 1 and 2 years old, though some are sexually mature as early as 6 months. Growth is fastest early on: on the chart above, typical length more than triples in the first four months, and by 12 months a typical dragon is already about 95% of its adult length. After a year, dragons mostly fill out and gain weight rather than length.
A fully grown dragon is usually 15–26 in (38–66 cm) long and weighs 300–550 g (10.6–19.4 oz), averaging around 400 g (reptile.guide). PetMD's care sheet describes adults as up to 24 inches long, with about half of that length being tail. The RSPCA gives a shorter adult length of about 45 cm (18 in), which fits the lower end of the range.
Male vs female bearded dragon size
Males are usually bigger. NC State Veterinary Hospital lists adult males at 21–24 inches and females at 16–19 inches, and reptile.guide gives similar figures (males 20–24 in, females 16–20 in). So a 17-inch adult female can be perfectly normal even though she sits at the small end of the chart.
What affects bearded dragon size and age?
The chart describes typical growth, not a target your dragon must hit. Size and age line up only loosely because of:
- Genetics: parents' size and breeding lines set the upper limit. Chewy quotes a breeder who names genetics and diet in the first two years as the main things that decide adult size.
- Diet: growing dragons need plenty of protein. PetMD says juveniles should eat about 70% insects. See our bearded dragon feeding schedule by age for meals per day at every stage.
- Heat and UVB lighting: dragons digest food and use calcium properly only with a warm basking area and UVB light. VCA links low UVB and poor calcium to metabolic bone disease, which stunts growth.
- Enclosure and competition: dragons kept in cramped enclosures or with bigger tank-mates may eat less and grow more slowly.
How old is my bearded dragon? Estimating age from size
If you adopted a dragon with no records, size is the easiest clue to its age while it is still growing. The Length → age mode reverses the size chart. It finds the age at which a typical dragon reaches your dragon's length (the best estimate). It also finds how early a fast-growing dragon and how late a slow-growing one could reach that size (the range). Adding weight narrows the range, and the calculator tells you if length and weight disagree.
| Total length | Best estimate | Likely age range | Life stage |
|---|---|---|---|
| 4 in (10 cm) | about 5 weeks | 4–7 weeks | Hatchling |
| 6 in (15 cm) | about 7 weeks | 6 weeks – 2 months | Hatchling |
| 8 in (20 cm) | about 2 months | 8 weeks – 3 months | Hatchling |
| 10 in (25 cm) | about 4 months | 3–5 months | Juvenile |
| 12 in (30 cm) | about 5 months | 4–7 months | Juvenile |
| 14 in (36 cm) | about 6 months | 5–9 months | Juvenile |
| 16 in (41 cm) | about 8 months | 5 months or older | Juvenile |
| 18 in (46 cm) | about 10 months | 6 months or older | Juvenile |
| 20 in (51 cm) | Adult-sized — age can't be told from size | 12 months or older | Sub-adult or adult |
| 22 in (56 cm) | Adult-sized — age can't be told from size | 12 months or older | Sub-adult or adult |
For example, a 10-inch dragon is most likely about 4 months old (3–5 months), and a 12-inch dragon about 5 months (4–7 months). Beyond about 15 inches the range has no upper limit: a 16-inch dragon could be a fast-growing juvenile of 8 months or a small adult female. Once a dragon is adult-sized (about 20 inches or more), its exact age can't be estimated from size: it could be one year old or ten. Chewy's guide makes the same point in a simpler way: under 4 inches is probably less than a month old, while 20 inches or longer is probably 8 months or older.
Know the age already? Convert it with the bearded dragon age calculator to see your dragon's age in human years and its life stage.
How to measure a bearded dragon safely
Every length on this page is total length, from the tip of the nose to the tip of the tail (reptile.guide). To get a reliable number:
- Measure when your dragon is warm and calm, for example after basking. A cold or stressed dragon may not lie still.
- Support its whole body and legs with one hand. Never hold or pull a dragon by the tail.
- Lay a soft tape measure or string along the spine, following the curve of the tail, and read it at the tail tip. For a wriggly dragon, photograph it next to a ruler on a flat surface and measure from the photo.
- Weigh it on a digital kitchen scale in grams, in a small tub if needed (subtract the tub's weight).
- Record both numbers monthly while it is growing. The trend over a few months tells you more than any single reading.
Bearded dragon tank size by age
Sources agree that babies can start smaller and adults need much more room. They disagree on how much. VCA Animal Hospitals gives a 20-gallon tank as the minimum for a juvenile and 60 to 100 gallons or larger for adults. VCA adds a sizing rule: the enclosure should be at least three times as long as your dragon's total length and at least 16 inches wide. PetMD's care sheet also says 20 gallons for juveniles.
| Age | Life stage | Typical length | Minimum enclosure | VCA 3× rule (length × width) |
|---|---|---|---|---|
| 1 month | Hatchling | 3.5 in | 20 gal minimum | 10.5 × 16 in (27 × 41 cm) |
| 3 months | Juvenile | 9.5 in | 20 gal minimum | 28.5 × 16 in (72 × 41 cm) |
| 6 months | Juvenile | 14.5 in | 20 gal minimum | 43.5 × 16 in (110 × 41 cm) |
| 9 months | Juvenile | 17.5 in | 20 gal minimum | 52.5 × 16 in (133 × 41 cm) |
| 1 year | Sub-adult | 19.5 in | 4 × 2 × 2 ft (120 × 60 × 60 cm), ~120 gal | 58.5 × 16 in (149 × 41 cm) |
| 18 months | Adult | 20.5 in | 4 × 2 × 2 ft (120 × 60 × 60 cm), ~120 gal | 61.5 × 16 in (156 × 41 cm) |
Why do some guides say 40 gallons and others 4 × 2 × 2 feet? Older care sheets, including PetMD's, list 40 gallons or more for an adult, which is roughly the size of a standard 40-gallon aquarium. More recent welfare guidance asks for much more floor space. The RSPCA calls 120 × 60 × 60 cm (about 4 × 2 × 2 ft, or 48 × 24 × 24 in) the minimum for one adult, and Chewy recommends a 4 × 2 × 2 ft, roughly 120-gallon enclosure as the permanent home. Using VCA's own 3× rule, a typical 20-inch adult needs an enclosure about 60 inches long, which is bigger than 40 gallons. We follow the larger, newer guidance. If you buy one enclosure for life, many keepers start with the adult size (Chewy).
Housing also changes with age. VCA warns that only one adult male should share an enclosure because adult males often fight, and that dragons housed together should be about the same size.
Signs of stunted growth in bearded dragons
A dragon that is small for its age is not automatically unwell. Genetics and sex matter, and females are naturally shorter. But slow growth combined with other signs can point to a husbandry or health problem. The most common cause of stunting discussed by vets is metabolic bone disease (MBD). VCA says it is most often seen in juvenile dragons under two years old and is usually caused by a diet high in phosphorus and low in calcium, too little vitamin D3, or not enough UVB light.
According to VCA, dragons with MBD may fail to thrive, fail to grow at a normal rate and seem weak. Other signs include:
- A swollen lower jaw, or a soft, bendy "rubber jaw" and softened facial bones
- Swollen back legs, trembling legs, or trouble holding the body up off the ground
- General weakness, or a dragon that stops gaining length or weight over several months
This is general information, not a diagnosis. If your dragon is small and shows any of these signs, see a reptile vet promptly. PetMD notes that metabolic bone disease and kidney disease are very common in dragons that haven't had proper care, and VCA says not every case can be fully resolved, so early treatment matters.
How the size calculator works
Length → age: best estimate = age where a typical dragon reaches that length · range = age where the fastest and slowest growers do
The calculator uses the growth chart above. For ages between chart points it draws a straight line, so a 4½-month-old gets a range halfway between 4 and 5 months. "% of adult size" compares the typical length at that age with the middle of the adult range (20.5 in). Enclosure advice comes from VCA, PetMD, the RSPCA and Chewy as described above. When you enter both length and weight, the estimate averages the two and the range covers only ages that fit both.
Planning meals as well? The bearded dragon feeding chart by age shows how many times a day to feed and how the insect-to-greens ratio changes as your dragon grows. Keep a snake as well? Our ball python size by age chart answers how big ball pythons get, with male and female growth charts and tank sizes. Thinking about a smaller lizard? See leopard gecko size by age for a leopard gecko growth chart, or the leopard gecko lifespan calculator for how long they live.
Frequently asked questions
What is the typical bearded dragon size by age?
On the growth chart used here, a bearded dragon is about 3 in at hatching, 8–11 in (20–28 cm) at 3 months, 11–18 in (28–46 cm) at 6 months, 15–24 in (38–61 cm) at 1 year and 15–26 in (38–66 cm) when fully grown at about 18 months.
How big is a 3 month old bearded dragon?
A 3-month-old bearded dragon is usually 8–11 in (20–28 cm) long and weighs 20–110 g (0.7–3.9 oz).
How big is a 6 month old bearded dragon?
A 6-month-old bearded dragon is usually 11–18 in (28–46 cm) long and weighs about 180–225 g (6.3–7.9 oz).
How big is a 9 month old bearded dragon?
Usually 14–21 in (36–53 cm) long and 250–350 g (8.8–12.3 oz).
How big is a 1 year old bearded dragon?
A 1-year-old bearded dragon is usually 15–24 in (38–61 cm) long and weighs 300–450 g (10.6–15.9 oz). Most keep filling out until about 18 months.
At what age is a bearded dragon full size?
Most bearded dragons reach full size at about 18 months (reptile.guide, Chewy). Adults are usually 15–26 in (38–66 cm) long and weigh 300–550 g (10.6–19.4 oz); males are typically larger than females.
How old is my bearded dragon if it is 10 inches long?
A 10-inch bearded dragon is most likely about 4 months old, with a likely range of 3–5 months.
How old is a 16 inch bearded dragon?
Probably about 8 months old, but the range is wide (5 months or older). A 16-inch dragon could be a fast-growing juvenile or a small adult female.
Can you tell a bearded dragon's age from its size?
Only while it is still growing. Size gives a useful range for dragons under about a year. Once a dragon is adult-sized (about 19.5 in or longer), its exact age can't be estimated from size, because adults of 2 and 10 years look the same size.
What is the bearded dragon tank size by age?
VCA gives 20 gallons as the minimum for a juvenile and 60–100 gallons or larger for adults, with a length at least 3× the dragon's total length. The RSPCA's minimum for one adult is 120 × 60 × 60 cm (about 4 × 2 × 2 ft). Older guides said 40 gallons for adults, but newer welfare guidance asks for more space.
How much should a bearded dragon weigh?
About 20–110 g (0.7–3.9 oz) at 3 months, 180–225 g (6.3–7.9 oz) at 6 months, 300–450 g (10.6–15.9 oz) at 1 year and 300–550 g (10.6–19.4 oz) as an adult (reptile.guide).
Why is my bearded dragon so small?
It may simply be a slow grower or a female. Genetics, diet, temperature and UVB all affect growth. Metabolic bone disease also stunts growth, so if a small dragon is weak or has a swollen jaw or legs, see a reptile vet.
This calculator gives an estimate for education and fun. Every pet ages differently — for health decisions, talk to your veterinarian.