Hedgehog Age Calculator

A 2-year-old hedgehog is about 37 in human years, right in the adult stage

There is no official chart for converting hedgehog years to human years. We could not find one in veterinary references or from animal hospitals, and the tables that circulate online come from a breeder site that does not say how they were made. So this calculator takes a different route. It matches three milestones in a hedgehog's life that have sources behind them with the same milestones in an American life, then joins them with straight lines. Sexual maturity at 2–3 months, taken as the midpoint of 2.5 months (Merck Veterinary Manual), is matched to puberty, using 12.5 years, the average age at first period reported by US women (CDC National Center for Health Statistics). An average lifespan of 4–6 years, taken as the midpoint of 5 years (Merck and VCA Animal Hospitals), is matched to US life expectancy at birth, 79.0 years in 2024. The longest recorded lifespan, 11.4 years in a zoo (AnAge database), is matched to the human record of 122 years 164 days.

On that basis, a 2-year-old hedgehog is about 37 in human years, in the middle of the adult stage, with 2 years to go before the senior stage begins at 4. Enter an age, a birthday or an adoption date in the calculator above to see the human age, the life stage and the time left until the average lifespan range. The life calendar below it has one cell per month, and the months your hedgehog has already lived are filled in with the color of each stage. Select a cell to see the human age and stage at that point. If you don't know the birthday, the calculator counts back from the adoption date and the age at adoption (8 weeks if you leave it blank) to estimate one.

When a human-age estimate is useful

A hedgehog's year passes much faster than a person's. By this calculator, once a hedgehog is full grown it adds about 1.16 human years every month, so its life stage can change within a few months. Putting the age in human terms helps you judge moments that are easy to miss when you only see a number of months or years.

• Understanding what stage a new hedgehog is in: A hedgehog brought home at about 8 weeks is roughly 9 in human terms, and sexual maturity (2–3 months) begins within a month. That means the time when it must not be housed with another hedgehog is close.
• Planning a check-up around 3 years: At 3 years a hedgehog is about 51 in human terms. The Merck Veterinary Manual says tumors are diagnosed most often after 3 years and that cardiomyopathy usually appears at 3 years or older. It is a good point to ask the vet to look at weight, breathing and the mouth during a routine visit.
• Starting senior care after 4 years: At 4 years a hedgehog is about 65 in human terms and entering the 4–6 year average lifespan range. Dental disease and oral cancer are common in older hedgehogs (VCA), so check the area around the mouth and how much your hedgehog eats more often.
• Thinking about adoption: The average is 4–6 years, and the Japan Ministry of the Environment gives up to 10 years. Hedgehogs live alone, so plan on one hedgehog per cage, and since a hedgehog below 68 °F (20 °C) can go into torpor, you will need to keep the temperature right all winter for that whole span.

How the calculation works

1. Three pairs of anchor points: (hedgehog 2.5 months, human 12.5 years), (hedgehog 5 years, human 79.0 years) and (hedgehog 11.4 years, human 122 years 164 days), plus birth at (0, 0).
2. Straight lines between the points: between 2.5 months and 5 years, human age = 12.5 + (hedgehog age in months − 2.5) ÷ (60 − 2.5) × (79.0 − 12.5). For 2 years (24 months) that is 12.5 + 21.5 ÷ 57.5 × 66.5 = 37.4, which rounds to 37.
3. Past 5 years: the line from 5 years (79.0) to 11.4 years (122.4) is gentler, adding nearly 7 human years per hedgehog year. Beyond 11.4 years the same slope is extended and the result is labeled "extended past the longevity record." The calculator goes up to 12 years 11 months.
4. Life stages: Baby (birth to 2 months), Juvenile (2 to 3 months), Adult (3 months to 4 years), Senior (4 to 6 years) and Long-lived (6 years and up). The baby stage ends at about 8 weeks, when the young are weaned and can be housed apart (Merck), and the juvenile stage ends at 3 months, the end of the sexual maturity range (Merck). We found no veterinary standard for when a hedgehog becomes a senior, so the 4–6 year average lifespan range is used as the senior stage and the period after it as the long-lived stage.
5. Entering a birthday or adoption date: the age is completed months up to today plus the fraction of the current month that has passed. With an adoption date, the calculator subtracts the age at adoption (7 days per week, or the same date for months) to get an estimated birthday. For a February 29 birthday, March 1 counts as the birthday in non-leap years.

Human age by hedgehog age

The first 2.5 months are the straight line from birth to puberty, so 1 month is 5 and 2 months is 10. From 3 months to 5 years, each month adds about 1.16 human years. After 5 years, each month adds about 0.6.

How long do hedgehogs live? Sources disagree

Merck and VCA, the veterinary sources, both give an average of 4–6 years, and this calculator matches the midpoint, 5 years, to human life expectancy. The Japan Ministry of the Environment lumps together the four species kept as pets (European, four-toed, Algerian and long-eared hedgehogs) and gives 5–10 years, which is longer. At the other end, a 2005 newsletter of the International Hedgehog Association, cited by a breeder site, puts the average lifespan of pet hedgehogs at 38.5 months (about 3 years 2 months). If you took 4 years as the life expectancy, the same hedgehog age would convert to an older human age; with 6 years, to a younger one.

What to keep in mind at each life stage

• Baby (birth to 2 months): Birth weight is 10–18 g. The eyes open at 14–18 days, and solid food starts at 3 weeks. Weaning comes at 4–6 weeks, and the young can be raised apart from the mother from about 8 weeks (Merck). Merck adds that handling them daily from 3 weeks can help them grow into gentle adults.
• Juvenile (2 to 3 months): Permanent teeth come in from 7–9 weeks, and sexual maturity is reached at 2–3 months (Merck). Gestation is short, 34–37 days (Merck), so separate any hedgehogs you brought home together before this stage. The Japan Ministry of the Environment also gives one hedgehog per cage as the rule, since they live alone.
• Adult (3 months to 4 years): Adult males weigh 400–600 g and females 300–400 g. Obesity is very common in pet hedgehogs, and a hedgehog that gets fat may not be able to roll up completely (Merck). Get a check-up at least once a year (VCA). Wobbly hedgehog syndrome (WHS) can start at any age, so see a vet if the hind legs become unsteady, whatever the age (Merck).
• Senior (4 to 6 years): This is the average lifespan range. Tumors are very common and a leading cause of death, and they are diagnosed most often after 3 years (Merck). Dental disease, tooth abscesses and oral cancer are common in older hedgehogs, so see a vet right away if the area around the mouth swells (VCA). Cardiomyopathy usually appears at 3 years or older, with signs such as labored breathing, less activity and weight loss (Merck).
• Long-lived (6 years and up): This is past the average lifespan range. In human terms that is 86 or older, and about 99 at 8 years. The longest lifespan recorded in AnAge for the four-toed hedgehog is 11.4 years, in a zoo.

Common mistakes

• Multiplying by a fixed number, such as "1 year = 18": Rules like this cannot be traced to any source. A hedgehog passes the equivalent of human puberty in its first 3 months and ages more slowly after that, so a single multiplier makes young hedgehogs come out too young and old ones too old.
• Treating a breeder's chart as official: The widely quoted table at Hedgehog Headquarters says only that it is an altered version of Laura Ledet's material and gives no method. It lists 40 at 3 years, 50 at 3 years 6 months and 60 at 3 years 8 months, so in one stretch the human age rises by 10 in just two months.
• Entering the adoption date as the birthday: If your hedgehog was already a few weeks old when you brought it home, those weeks need to be added. If you don't know the birthday, choose "Adopted" and enter the age you were told at adoption. Left blank, the age at adoption is counted as 8 weeks.
• Splitting lifespan by "large" and "small" varieties: Merck's average of 4–6 years is for the four-toed hedgehog, and the Japan Ministry of the Environment gives 5–10 years for the four pet species taken together. We found no veterinary source that divides lifespan by body size or variety, so this calculator has no variety setting.
• Setting the room to what feels comfortable to you: Below 68 °F (20 °C) a hedgehog can go into torpor (Merck). Merck gives 72–90 °F (22–32 °C) for housing, best at 75–85 °F (24–29 °C), and the Japan Ministry of the Environment gives about 68–81 °F (20–27 °C) as the suitable range. If the room in your home drops below 68 °F on winter nights, check the heating first.

Limitations

• We found no study that directly compares hedgehog aging with human aging. This value is an estimate from three anchor points joined by straight lines, and each hedgehog's health is different.
• The result assumes an average lifespan of 5 years. Sources range from an average of 38.5 months to 5–10 years, so a different assumption gives a different human age for the same hedgehog.
• The human anchor points use US figures: life expectancy at birth of 79.0 years (2024) and an average age at first period of 12.5 years, reported by women aged 15–44 surveyed in 2013–2017. The median in that survey was 11.9; the calculator uses the mean. Because the menarche figure comes from women only, it serves only as a rough marker for puberty.
• The senior stage starting at 4 years is borrowed from the average lifespan range, not set by a veterinary standard. Changes in weight, appetite and gait matter more as warning signs than age does.
• A result entered by adoption date is an estimate that assumes the age at adoption is correct.
• If you are worried about your hedgehog's health, have it examined by a veterinarian who treats exotic animals rather than relying on any calculator result. Your entries are calculated in this browser only and are never sent to a server.

Sources

• 01MSD/Merck Veterinary Manual — Overview of Four-Toed (African Pygmy) HedgehogsAverage lifespan 4–6 years, sexual maturity at 2–3 months, gestation 34–37 days, birth weight 10–18 g, eyes open at 14–18 days, permanent teeth at 7–9 weeks, weaning at 5–6 weeks (solid food from 3 weeks), adult males 400–600 g and females 300–400 g — checked 2026-10-22
• 02MSD/Merck Veterinary Manual — Management of Four-Toed (African Pygmy) HedgehogsWeaning at 4–6 weeks, housed apart from 8 weeks, daily handling from 3 weeks, housing temperature 72–90 °F (22–32 °C) and best at 75–85 °F (24–29 °C)
• 03MSD/Merck Veterinary Manual — Diseases of Four-Toed (African Pygmy) HedgehogsTumors are a very common leading cause of death, diagnosed most often after 3 years (also at 1 year), more than 80% malignant in one survey, cardiomyopathy usually at 3 years or older, obesity very common, WHS at any age, torpor below 68 °F (20 °C)
• 04VCA Animal Hospitals — Hedgehogs: OwningUsually 4–6 years (some live longer), a check-up at least once a year, dental disease, tooth abscesses and oral cancer common in older hedgehogs
• 05Japan Ministry of the Environment — Household pet care and keeping manual, 11. Hedgehogs (Japanese)Four pet species, lifespan 5–10 years, breeding from about 2–8 months of age, independent at 45–60 days, suitable temperature 20–27 °C (68–81 °F), one hedgehog per cage
• 06AnAge (Human Ageing Genomic Resources) — Atelerix albiventrisMaximum longevity 11.4 years (zoo, data quality High), female sexual maturity at 84 days
• 07Guinness World Records — Oldest person everJeanne Louise Calment (France), 122 years 164 days, died Aug 4, 1997
• 08CDC National Center for Health Statistics — Mortality in the United States, 2024 (NCHS Data Brief No. 548)Life expectancy at birth 79.0 years in 2024 (males 76.5, females 81.4), published January 2026 — checked 2026-10-11
• 09CDC National Center for Health Statistics — Trends and Patterns in Menarche in the United States: 1995 through 2013–2017 (National Health Statistics Reports No. 146)Mean age at menarche 12.5 years and median 11.9 years among women aged 15–44, National Survey of Family Growth 2013–2017, published Sep 10, 2020 — checked 2026-10-11
• 10Hedgehog Headquarters — LongevityA breeder site's conversion table (altered from Laura Ledet's material, no method given), quoting an International Hedgehog Association newsletter average of 38.5 months (2005)

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