Rabbit Age Calculator

A 2-year-old rabbit is about 22–34 in human years, and the bigger the rabbit, the faster it ages

There is no official chart for converting rabbit years to human years. We could not find one in the Merck Veterinary Manual, in material from the UK's RSPCA and RWAF (the Rabbit Welfare Association & Fund), or in House Rabbit Society material from the US. The rule that shows up in most searches, "20 in the first year, then 6 more every year", does not say how it was made either. So this calculator matches three milestones in a rabbit's life that have sources behind them with the same milestones in a human life, and joins the points with straight lines. Sexual maturity is matched with human puberty (an average age at first period of 12.5 years for US women), the middle of the average lifespan range is matched with human life expectancy (79.0 years in the US in 2024), and the oldest rabbit in the Guinness records, 18 years 10.75 months, is matched with the longest human life on record, 122 years 164 days.

Rabbits differ a lot in body size by breed, and the age at maturity and the lifespan depend on size. RWAF gives about 12–13 years for small breeds, 9–10 years for medium breeds and 4–7 years for large and giant breeds. That is why the same 2 years comes out at about 22 in human years for a small rabbit, about 24 for a medium one and about 34 for a large one. Enter the size and the age (or birthday or adoption date) in the calculator above to see the human age and life stage. The care map below shows, next to the current age, when to switch from alfalfa to grass hay, when to neuter and when senior care begins.

When and why to convert to human years

A rabbit's first year goes by very fast, and the age at which a rabbit becomes a senior differs by several years depending on size. Converting to human years makes it easier to see what needs attention now.

• Knowing when to change the diet: the House Rabbit Society's diet by age gives unlimited alfalfa hay and alfalfa pellets up to 7 months, then unlimited grass hay from 7 months with pellets cut back to timothy pellets. Seven months for a medium rabbit is about 14 in human years.
• Not missing the neutering window: RWAF recommends 10–12 weeks for males, when the testicles descend, and 16–20 weeks for females, and says surgery in a female gets harder after about 9 months because of fat around the uterus. Merck gives around sexual maturity, usually 6 months.
• Knowing the uterine cancer risk of an unneutered female: the RSPCA says about 80% of unneutered females develop uterine cancer after age 3, and RWAF says up to 85% develop reproductive cancers by age 5.
• Knowing when senior care begins: RWAF treats rabbits as seniors from 8 years for small breeds, 6 years for medium breeds and 4 years for large breeds. In human years that is about 54–60 for all three. For a large rabbit, 4 is the age to start checkups more often.

How it is calculated

1. Anchor points by size: the middle of the sexual maturity range (Merck, RSPCA) and the middle of the average lifespan range (RWAF; for an unknown size, RSPCA and Rabbit.org) are set as in the table below. The Guinness record of 18 years 10.75 months and birth at (0, 0) make four points. A month is counted as 365.25 ÷ 12 days (30.44 days).
2. Straight lines between the points: between sexual maturity and the average lifespan, human age = 12.5 + (rabbit months − months at sexual maturity) ÷ (months at the average lifespan − months at sexual maturity) × (79.0 − 12.5). For a medium rabbit of 2 years (24 months) that is 12.5 + (24 − 4.25) ÷ (114 − 4.25) × 66.5 = 24.47, which rounds to about 24.
3. Past the average lifespan: a gentler segment runs from the middle of the average lifespan (human 79.0) to the Guinness record of 18 years 10.75 months (human 122.4). Beyond the record the calculator shows "Over 122 yr" instead of a number, and it calculates up to 19 years 11 months.
4. Life stages: Baby (birth to 8 weeks, with the RSPCA giving 4–8 weeks as when weaning starts), Young (8 weeks to sexual maturity), Teen (sexual maturity to 1 year, up to the end of "Young Adult", 7 months to 1 year, in the House Rabbit Society diet chart), Adult (1 year to the start of senior age), Senior (start of senior age to the end of the average lifespan) and Long-lived (after the average lifespan).
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.
6. The axis of the care map: so much changes in the first year that the left 40% of the map stretches birth to 1 year, and the other 60% covers 1 year to the end of the average lifespan for that size plus 2 years (the end of the next year if the rabbit is older, up to 20 years).

The last column is the age at which senior age starts, converted to human years. Small means breeds such as the Netherland Dwarf, Polish and Dutch, medium means the dwarf lop up to a weight of about 3.5–4 kg, large means breeds such as the New Zealand White and Belgian Hare, and giant means breeds such as the Continental Giant. Sexual maturity comes from Merck and the RSPCA, and the average lifespan and senior age come from RWAF's guidance by size. RWAF groups large and very large breeds together, so large and giant differ only in sexual maturity. When the size is unknown, the calculator uses the RSPCA's "3–8 months" and "8–12 years", and for the start of senior age it uses the "Senior Diet (6 years +)" in the House Rabbit Society diet chart. The RSPCA says senior age comes between 5 and 8 years.

Human age by rabbit age

These values use US figures (puberty at 12.5, life expectancy of 79.0 years). You can check the same cells in the calculator above by changing the size. Each number is a human age in years.

Large and giant rabbits are seniors from age 4, and past 7 years they are beyond the average lifespan (long-lived). Small rabbits only become seniors at 8, so the same 8 years is about 54 in human years for a small rabbit and about 87 for a large one. The reference sources for the table were checked against the originals on October 23, 2026.

How long rabbits live: lifespans differ by source

The "average lifespan" and the "median age at death" are different numbers. The 4.3 years from VetCompass counts rabbits that died in veterinary records during the study, so it includes rabbits that died young of illness or accidents, while long-lived rabbits are left out because they did not die during the study. Of the 267 deaths with a recorded cause in that study, the most common cause was flystrike (29 rabbits, 10.9%), followed by poor appetite and collapse. At any age, it is a good idea to check every day that your rabbit is eating and that the area around its rear end is clean.

The Guinness record holder, Flopsy, was a rabbit caught in the wild that lived 18 years 10.75 months in Tasmania, Australia. Her age when caught is unknown, so her real age could have been higher, and AnAge says the record cannot be confirmed. Guinness also published a story in 2013 about Do, a Jersey Wooly in the US who died at 17 years 2 weeks. This calculator uses the official record of 18 years 10.75 months as an anchor point and states this caveat alongside it.

Diet and care that change with age

• Alfalfa only while young: the House Rabbit Society says to give alfalfa hay only to nursing mothers and young rabbits. Merck says that an adult eating alfalfa-based feed for a long time can suffer kidney damage and calcium carbonate deposits in the urinary tract, and recommends unlimited timothy hay for adults.
• The amounts in the table have to fit the body weight: the adult (1–5 years) row gives amounts per 6 lb (about 2.7 kg) of body weight, but the 1/2 cup, 1 cup and 2 cups in the young adult and senior rows come without a body weight. The same amount can be too much or too little for rabbits of very different sizes, so set the amount with your vet while watching weight changes.
• Hay stays central in old age: RWAF says senior rabbits also need plenty of fresh hay, water and leafy greens every day. Regular checkups are especially important for older rabbits so that health problems are found early (RSPCA).
• Weaning: Merck says domestic rabbit kits wean at about 6 weeks, and the RSPCA says weaning starts at 4–8 weeks.

When to neuter, and uterine cancer in females

According to the RSPCA, the testicles of a male descend and become visible at 10–12 weeks, and before that it is hard to tell males from females. RWAF says that for a young rabbit you have just taken in, a male is best neutered right at 10–12 weeks when the testicles descend, and a female can be done from a similar age but 16–20 weeks is preferred because the uterus is very small. It adds that after about 9 months the fat around the uterus builds up and surgery in a female gets harder. Merck recommends surgery around sexual maturity, usually 6 months. The neutering lane on the care map shows this range (10 weeks to 6 months, shaded lighter up to 9 months).

The biggest reason to spay a female is uterine adenocarcinoma. Merck cites reports of up to 80% by age 3 in some strains, the RSPCA says about 80% of unneutered females develop uterine cancer after age 3, and RWAF says up to 85% develop reproductive cancers by age 5. The numbers and the age conditions differ by source, but all agree that the risk rises sharply with age. The uterine cancer lane on the map darkens from age 3 and is darkest from age 5. If a female is already older, discuss the pros and cons of surgery with your vet.

Common mistakes

• Using one formula and ignoring size: with "20 in the first year, then 6 more every year", a 5-year-old rabbit is 44 whatever its size. By RWAF's guidance a large rabbit is a senior from age 4, so treating a 5-year-old large rabbit as middle-aged delays senior care.
• Reading the median age at death as the lifespan: the 4.3 years from VetCompass is the median for rabbits that died in veterinary records. It does not mean rabbits usually live only 4 years.
• Keeping adults on alfalfa: alfalfa is high in protein and calcium and suits growing rabbits. From 7 months, switch to grass hay as the main food.
• Entering the adoption day as the birthday: a rabbit from a pet shop or shelter has already lived several weeks to several months. Choose "Adopted" and enter the age at adoption in weeks or months to calculate from an estimated birthday.
• Guessing the size of a mixed-breed rabbit: if you don't know the breed, choose "Not sure". An adult weight above about 3.5–4 kg is closer to RWAF's large group.

Limits and cautions

• The human age is an estimate that lines up three points in life and joins them with straight lines. It does not mean that rabbits and people age at the same rate, and it does not match body condition or disease risk exactly.
• The human anchor points use US figures: an average age at first period of 12.5 years, reported by women aged 15–44 surveyed in 2013–2017, and life expectancy at birth of 79.0 years in 2024. Using another country's figures changes the human age a little for the same rabbit.
• The lifespan and senior age by size are RWAF's "approximate guidance", and RWAF itself says that old age is not decided by age alone and each rabbit should be assessed.
• The diet lanes on the care map follow the House Rabbit Society's diet chart, and organizations recommend slightly different approaches. If a rabbit has a long-term illness or is losing weight, your vet's advice comes first.
• This calculator does not diagnose anything. If your rabbit stops eating or its droppings decrease, take it to a vet who treats exotic animals right away, whatever its age. Your entries are calculated in this browser only and are never sent to a server.

Sources

• 01MSD/Merck Veterinary Manual: Management of RabbitsRevised July 2026; sexual maturity small 3.5–4 months, medium 4–4.5 months, giant 6–9 months, kits weaned at about 6 weeks, testicles descend at 10–12 weeks, neutering around sexual maturity usually at 6 months, in some strains 80% uterine adenocarcinoma by age 3
• 02MSD/Merck Veterinary Manual: Nutrition of RabbitsRevised July 2026; unlimited timothy hay for adults, long-term alfalfa-based feed linked to kidney damage and calcium carbonate deposits in the urinary tract
• 03RSPCA: Pet rabbitsUsually 8–12 years, weaning starts at 4–8 weeks, puberty at 3–5 months, fully grown at 7–9 months, senior between 5 and 8 years, sexual maturity 3–8 months (small 3.5–4, medium to large 4–4.5, giant 6–9 months), testicles at 10–12 weeks
• 04RSPCA: Caring for an older rabbitLifespan linked to size and smaller rabbits tend to live longer, about 80% of unneutered females get uterine cancer after age 3, regular checkups for older rabbits
• 05RWAF (Rabbit Welfare Association & Fund): Caring for senior rabbitsSmall 12–13 years and senior from 8, medium (dwarf lop to about 3.5–4 kg) 9–10 years and senior from 6, large and giant 4–7 years and senior from 4, reproductive cancer in up to 85% of unneutered females by age 5
• 06RWAF: Neutering, castration and spayingMales at 10–12 weeks when the testicles descend, females at 16–20 weeks, surgery in a female is harder after about 9 months
• 07House Rabbit Society: DietDiet chart by age (3–7 weeks and 7 weeks–7 months unlimited alfalfa hay and alfalfa pellets, new vegetables from 12 weeks, 7 months–1 year unlimited grass hay and timothy pellets, senior diet from 6 years), alfalfa only for nursing mothers and young rabbits
• 08Rabbit.org: How long do rabbits live?(Paige K Parsons)Indoor rabbits usually 8–12 years (depending on size, breed and care), outdoor rabbits about 3–5 years
• 09PDSA: How long do pets live?Healthy rabbits 7–10 years on average
• 10O'Neill DG et al. (2020), Morbidity and mortality of domestic rabbits (Oryctolagus cuniculus) under primary veterinary care in England, Veterinary Record6,349 rabbits from 107 practices, median age at death 4.3 years for the 370 that died during the study (interquartile range 2.1–7.0, range 0.1–14.4), males 5.2 and females 3.7, most common recorded cause of death flystrike in 29 rabbits (10.9% of 267)
• 11AnAge (Human Ageing Genomic Resources): Oryctolagus cuniculusMaximum longevity 13 years (captive, zoo and park records), rarely past 9 years in the wild or in captivity, Flopsy's 18.8 years is a record that cannot be confirmed, domestic females can breed at 3 months
• 12Guinness World Records: Oldest rabbit everFlopsy, a wild rabbit caught on August 6, 1964, died 18 years 10.75 months later in Longford, Tasmania, Australia, average lifespan 5–10 years
• 13Guinness World Records: My Story: Jenna Antol on owning Do, the world's oldest rabbitPosted February 6, 2013; the Jersey Wooly Do lived 17 years 2 weeks
• 14Guinness World Records: Oldest person everJeanne Louise Calment (France), 122 years 164 days, died Aug 4, 1997
• 15CDC 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
• 16CDC 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

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