Wildlife Guides · Baby Animal Identification
Baby Opossum Age Chart: How Old Is That Joey?
Opossums are the one baby animal you can age with a ruler. One measurement decides whether the joey in front of you is an orphan or a young adult — and you almost certainly have the ruler in your wallet.
About the photographs on this page. Every image here was taken by licensed wildlife rehabilitators at CritterAid Wildlife Rescue and is used with their permission.
On this page
The Dollar Bill Test
Rehabilitators across North America use one number for opossums, and it is refreshingly simple. Measure the joey's body only — tip of the nose to the base of the tail. Do not include the tail. The tail on an opossum is nearly as long as the body, so including it is the single most common measuring mistake and it will give you an answer that is badly wrong.
Too young to survive alone. It is an orphan regardless of how healthy it looks, and it needs a licensed rehabilitator. There is no version of this where you leave it and it works out.
Old enough to be independent. If it is alert, moving well, and uninjured, leave it alone. A small opossum living on its own is normal, not an emergency.
No ruler? Use a dollar bill. A US bill is about 6.1 inches long. Lay the joey's body alongside it: clearly shorter than the bill means it needs help, and there is no ambiguity. Around the same length is borderline — get a real measurement. Clearly longer than the bill, and you are probably looking at an independent young opossum.
Where agencies differ, and why it's worth knowing. Seven inches is the common benchmark, used by Wisconsin DNR among others. Some agencies set it more conservatively — Virginia DWR uses 8 inches and a weight over 200 grams, about 7.25 ounces. If the joey is sitting between 7 and 8 inches, treat it as borderline and call a rehabilitator rather than deciding on your own. The cost of being wrong is not symmetrical.
Baby Opossum Age Chart, Stage by Stage
Opossums are the only marsupial in North America, and that changes everything about how they develop. A joey is born after roughly 13 days of gestation — the shortest of any mammal on the continent — at a stage most animals would still call embryonic. It finishes developing in the pouch instead of the womb.
Born about the size of a honeybee, blind, earless, and barely formed — but with front limbs developed enough to climb. The newborn crawls unaided from the birth canal into the pouch and latches onto a teat, where it stays fused for weeks.
- Weight: around 0.13 grams — roughly a grain of rice
- Litter: up to 20 born, but a female has around 13 teats, so not all survive the crawl
- You will not encounter this stage unless you are checking the pouch of a dead mother
Still permanently attached to the teat. Fur begins to appear, the face takes shape, and the joey grows from rice-grain to roughly mouse-sized across these weeks.
- Eyes: sealed throughout
- Body: pink and thinly furred early, filling in toward the end of this window
- Detaching: a joey this young cannot be pulled off a teat — doing so causes serious injury
The eyes open at around two months, and the joey begins detaching and making short trips out of the pouch. This is the first stage at which one could conceivably be found on the ground.
- Body length: roughly 3–4 inches, nose to base of tail
- Weight: around 40–80 grams
- Found alone: a genuine emergency — less than half the independence size
This is the stage you are most likely to find. Joeys ride clinging to their mother's back while she forages at night, and they fall off. She keeps walking.
- Body length: roughly 4–6.5 inches — under the 7-inch line
- Weight: about 40–190 grams
- Sound: a soft sneezing or hissing call, which is how joeys signal their mother. If you hear it, listen for others nearby — they rarely fall off one at a time
- Found alone: needs a rehabilitator
At around four months the young disperse and live alone. Opossums are solitary animals — there is no family group to return to and no extended juvenile period.
- Body length: 7–9 inches and up, nose to base of tail
- Weight: over 200 grams, about 7.25 ounces
- Behavior: alert, flees, or stands its ground with an open mouth and drooling — all normal, healthy responses
- Needs from you: nothing
Baby Opossum Size Chart by Age
Length is the primary measure for opossums, with weight as the confirmation. Both are more reliable than appearance, because a well-fed young joey can look deceptively sturdy.
| Age | Body length | Weight | Eyes | Where it lives | Alone = ? |
|---|---|---|---|---|---|
| 0–10 days | Under 1 in | ~0.13 g | Sealed | Attached in pouch | Emergency |
| 10–55 days | 1–3 in | Up to ~40 g | Sealed | Attached in pouch | Emergency |
| 55–70 days | 3–4 in | 40–80 g | Open | In and out of pouch | Needs help |
| 2.5–3.5 mo | 4–6.5 in | 40–190 g | Open | On mother's back | Needs help |
| 4 mo + | 7–9 in + | 200 g + | Open | On its own | Leave it |
All lengths are nose to base of tail, tail excluded. An opossum's tail runs nearly the length of its body, so measuring the whole animal will roughly double your number and push a joey that needs help into the "leave it" column.
Why She Won't Come Back
If you have read advice about other baby animals, you have probably been told to warm the animal, put it back out at dusk, and give the mother a night to retrieve it. That does not work for opossums, and following it will cost the joey its life.
A mother opossum carries her young on her back while foraging. When one loses its grip, she does not notice, does not stop, and does not return. Wisconsin DNR states it plainly: if a fallen joey cannot catch up and climb back on, it is left behind. There is no reunion window because there is no reunion behavior.
With a raccoon kit, waiting one night is usually the right call — the mother is actively looking. With a baby cottontail, walking away is usually the right call — the mother is nearby by design. With an opossum under 7 inches, neither applies. Measure, then call.
The one thing worth doing before you leave the area: look around, and listen. Joeys rarely come off alone, and their contact call is a soft sneeze or hiss. Finding one on a driveway often means finding three more within a few yards.
Checking a Dead Mother's Pouch
This is unpleasant and it saves more opossums than anything else on this page. A female killed on a road in spring or summer is very likely carrying young, and pouch joeys can survive their mother by many hours. Most drivers never think to look.
If it is safe to stop and safe to approach the road, put on gloves and check the pouch on the abdomen. If there are joeys inside, do not attempt to pull them off the teats — young ones are physically fused and pulling causes fatal injury to the mouth and jaw. Move the entire mother, joeys attached, into a ventilated box and call a rehabilitator immediately. They are equipped to detach them properly.
Never put yourself in traffic for this. A live person is worth more to wildlife than a recovered litter.
When It Needs Help Tonight
Any opossum under 7 inches needs a rehabilitator. So does one of any size showing these signs:
Contact with a cat or dog
A medical emergency even with no visible wound. Cat saliva alone is lethal to small mammals without antibiotics.
Cold, wet, or crying nonstop
All three mean the joey has been without its mother long enough to be in real trouble.
Fly eggs
Small clusters that look like grains of rice, usually around the eyes, ears, nose, or genitals. This moves fast.
Visible injury or a known dead mother
Bleeding, an open wound, an obvious limb injury, or a mother found dead nearby.
While you wait, do these four things and nothing else
- Gloves on. Opossums have 50 teeth, more than any other North American land mammal, and a frightened joey will use them.
- Ventilated box, soft cloth, dark and quiet. Away from pets, children, television, and conversation.
- Gentle heat. A bottle of warm water or a sock of uncooked rice under the cloth — never directly against the animal.
- Nothing to eat, nothing to drink. No milk of any kind, and no water by syringe — joeys aspirate easily and drown. Feeding a dehydrated animal causes serious harm.
Opossums and Rabies
Worth stating clearly, because it is the fear that gets healthy opossums killed: opossums are remarkably poor hosts for rabies. Their body temperature runs several degrees cooler than most mammals, low enough that the virus struggles to establish. Confirmed rabid opossums are genuinely rare compared with raccoons, skunks, foxes, and bats.
That is not license to handle one bare-handed. Any wild mammal can bite, bites can carry other infections, and a bite or scratch from any wild animal warrants a call to your local health department. But the drooling, hissing, open-mouthed display that frightens people is a bluff, not a symptom. It is the same performance as playing dead — a threat display from an animal with almost no other defense.
"Playing possum" is not an act. It is an involuntary catatonic state triggered by extreme fear, closer to fainting than to strategy. An opossum in that state cannot choose to snap out of it and may stay down for minutes or hours. If you find one apparently dead with no injury, leave it undisturbed and check back later.
Possum or Opossum?
Both terms are used constantly in the United States and they point to the same animal here: the Virginia opossum, Didelphis virginiana. "Possum" is simply the common shortening.
Strictly, true possums are a different family of marsupials native to Australia and New Guinea — brushtail possums, ringtails, and their relatives. They are not found in North America and are not what you have in your yard. If you are in the US or Canada and looking at a grey animal with a white face, a pink nose, and a long bare tail, it is an opossum, and everything on this page applies.
Finding a Licensed Wildlife Rehabilitator
Rehabilitators are state-licensed and are overwhelmingly unpaid volunteers working from home. Opossums are one of the most commonly admitted species in spring and summer, which means two things: most rehabbers are experienced with them, and many are at capacity during peak season. Call early, and call more than one if the first is full.
Most state wildlife agencies publish a searchable directory. Michigan's is the DNR Directory of Licensed Wildlife Rehabilitators; search your own state's natural resources or fish and wildlife department for the equivalent.
Have three things ready when you call: the body measurement in inches with the tail excluded, where you found it and how long ago, and whether a cat or dog was involved. That measurement is the first question they will ask.
Photo credit
All photographs on this page were provided by CritterAid Wildlife Rescue, a 501(c)(3) wildlife rescue in Tarpon Springs, Florida, and are used with permission. CritterAid takes in orphaned and injured wildlife year-round and runs entirely on donations. If this guide helped you, please consider supporting their work.
Common Questions
How can I tell how old a baby opossum is?
Measure its body from the tip of the nose to the base of the tail, excluding the tail. Roughly 3 to 4 inches puts it around two months, 4 to 6.5 inches puts it in the back-riding stage at two and a half to three and a half months, and 7 inches or more means it is around four months and independent.
What size baby opossum can survive on its own?
Seven inches from nose to base of tail is the common benchmark, and some agencies use a more conservative 8 inches plus a weight over 200 grams. Under that size the joey is an orphan and needs a licensed rehabilitator, no matter how healthy it looks.
Will a mother opossum come back for a baby that fell off?
No. Unlike raccoons and many other mammals, a mother opossum does not notice a joey falling from her back and does not return for it. There is no reunion window with this species — measure the joey and call a rehabilitator if it is under seven inches.
Do baby opossums carry rabies?
Rarely. An opossum's body temperature is low enough that the rabies virus struggles to establish, and confirmed cases are uncommon compared with raccoons, skunks, foxes, and bats. Still wear gloves — any wild mammal can bite, and any bite warrants a call to your local health department.
What do baby opossums eat?
Their mother's milk while in the pouch, then an omnivorous adult diet of insects, fruit, carrion, and small animals from around three months. Never offer food or water to a found joey — opossums aspirate liquid very easily, and feeding a dehydrated animal causes serious harm. That is a rehabilitator's job.
Should I check the pouch of a dead opossum?
Yes, if it is safe to approach. Females killed on roads in spring and summer are often carrying young who can survive for hours afterward. Do not pull joeys off the teats — move the mother and attached young together in a ventilated box and call a rehabilitator immediately.
Is it a possum or an opossum?
In North America both words mean the Virginia opossum. True possums are a separate group of marsupials native to Australia and New Guinea and are not found here.
Can I keep or raise a baby opossum?
In most states it is illegal without a permit, and joeys have specific dietary and housing requirements that are very difficult to meet. Hand-raised opossums frequently cannot be released. Contact a licensed rehabilitator instead.
Keep Reading
Baby Raccoon Age Chart
Stage-by-stage photos for raccoon kits, whose mothers do come back — and how to give her the chance.
Baby Rabbit Age Chart
Wild cottontails are independent at three weeks, which is why most "rescued" bunnies were never orphaned.
What Do Opossums Eat?
The adult diet, and what an opossum's presence actually does for the land it lives on.
All Wildlife Guides
Identification and habitat guides written from a working 30-acre habitat in mid-Michigan.
The Whispering Woods
A children's book about a girl named Elara, a puppy named Scout, and the forest animals they meet — written on the same 30 acres of Michigan habitat where the wildlife in these guides actually lives.
See the bookPrivate Lands Wildlife is a 501(c)(3) wildlife habitat nonprofit in Gratiot County, Michigan. This guide is educational and is not a substitute for advice from a licensed wildlife rehabilitator, veterinarian, or public health authority. If you have been bitten or scratched by a wild animal, contact your local health department.