Why Is My Guinea Pig Not Eating? Causes & Emergency Signs
If your guinea pig suddenly stops eating, it should always be taken seriously. Guinea pigs have sensitive digestive syst…
Educational Reference Ranges · No Account Required · Instant Result
What This Tool Checks
- Compares weight against typical healthy ranges
- Adjusts ranges for sex and age group
- Shows a visual weight scale for context
- Provides educational guidance and monitoring tips
Free to use, no sign-up
Quick Answer
A healthy guinea pig's weight depends on both sex and age: adult females average 700-900g, while adult males (who run larger) average 900-1,200g (Merck Veterinary Manual) — this tool compares an adult's weight against the average for their sex, and gives reference points and tracking advice for growing pups and young adults.
The Basics
How This Tool Works
Enter your guinea pig's weight, sex, and age bracket to see how it compares to typical ranges.
- You provide your guinea pig's weight, sex (male or female), and age bracket (baby, young adult, adult, or senior).
- For adults and seniors, the calculator compares that weight against the average range for their sex, plus a tolerance band just above the maximum. For babies and young adults it shows reference points instead of a verdict.
- You get a status — below, within, above or well above the typical range — along with educational guidance for that status.
Reference Chart
Guinea Pig Weight Chart by Age and Sex
Typical weights from the Merck Veterinary Manual's physiological data for guinea pigs, shown in grams, ounces and pounds. Males run heavier than females. Growing pups and young adults have no single published range, so the checker shows reference points and tracking advice for them instead of a verdict.
| Stage | Female (sow) | Male (boar) |
|---|---|---|
| Birth | 100-120 g 3.5-4.2 oz · range 45-120 g | 100-120 g 3.5-4.2 oz · range 45-120 g |
| Weaning (about 3 weeks) | roughly 180 g 6.3 oz | roughly 180 g 6.3 oz |
| Adult average | 700-900 g 24.7-31.7 oz · 1.54-1.98 lb | 900-1,200 g 31.7-42.3 oz · 1.98-2.65 lb |
These are averages, not limits: some healthy guinea pigs sit above or below them, and pregnant sows weigh more. Check body condition (ribs felt under a thin layer of padding, a waist from above) as well as the scale. Individual pigs and some breeds may weigh more or less. A sudden or steady drop in weight matters more than any single number, so weigh weekly and contact your vet if your guinea pig loses weight without an obvious reason.
Preventive Health
Why Weekly Weight Checks Matter
A digital kitchen scale and two minutes per week can make a significant difference to your guinea pig's health outcomes. Here's why regular weighing is one of the most valuable habits a guinea pig owner can build.
Early Illness Detection
Guinea pigs are prey animals that instinctively mask signs of illness until a condition has become serious. Unexplained weight loss, even a small amount, is often the first detectable signal that something is wrong. Weekly weighing gives you a data point that visible observation cannot reliably provide.
Appetite Monitoring
Weight is a direct reflection of food intake over time. A guinea pig that is secretly eating less - due to dental problems, social competition at food sources, or reduced appetite from illness - will show it in the scale reading before any other observable sign appears.
Growth Tracking
For baby and young adult guinea pigs, regular weigh-ins confirm that growth is on track. Pups grow quickly, from roughly 100-120 g at birth to about 180 g at weaning, and a growth plateau can indicate inadequate nutrition, parasite burden, or an underlying health concern that needs vet investigation.
Senior Health Monitoring
Senior guinea pigs (5+ years) are at increased risk of dental disease, tumours, kidney decline, and heart conditions - all of which cause weight loss as an early symptom. For seniors, bi-weekly or even weekly weighing combined with regular exotic vet check-ups is considered a gold standard of care.
Underweight
Common Causes of Weight Loss in Guinea Pigs
Weight loss in guinea pigs can have many causes, most of which respond well to early intervention. The following are among the most frequently seen in practice. This list is educational only - never use it to self-diagnose your guinea pig.
- ● Dental disease: Overgrown teeth, malocclusion, and molar spurs are among the leading causes of weight loss in guinea pigs. A guinea pig with dental pain often reduces hay consumption first, causing rapid weight loss. Signs include drooling, chewing on one side, or dropping food.
- ● Illness and infection: Upper respiratory infections, urinary issues, and systemic illness all suppress appetite and increase metabolic demand, resulting in weight loss. Weight loss is often the first measurable indicator before other symptoms appear.
- ● Social competition: A dominant guinea pig may monopolise food and water sources, leaving subordinate animals unable to eat adequately. Providing multiple stations at opposite ends of the cage can resolve this.
- ● Stress and environmental change: A move, new cage mate, loud environment, or significant routine disruption can suppress appetite and lead to short-term weight loss. Guinea pigs are highly sensitive to change.
- ● Inadequate diet: A diet too low in quality hay, or with too little Vitamin C, can lead to gradual weight loss. Fresh leafy vegetables and unlimited high-quality hay are essential for maintaining weight.
When to See a Vet
Weight loss in guinea pigs always warrants monitoring and often warrants veterinary attention. Seek a vet promptly if:
- Weight has dropped by roughly 50g or more in a single week (a common owner rule of thumb, not a fixed veterinary cut-off)
- Weight loss continues for two or more consecutive weeks
- Your guinea pig is eating noticeably less hay or vegetables
- You notice drooling, difficulty chewing, or dropping food
- Lethargy, hunched posture, or laboured breathing accompany the weight loss
- Your guinea pig is a senior (5+ years) - weight loss at this age needs prompt assessment
This tool is for educational monitoring only and does not replace veterinary diagnosis.
Overweight
Common Causes of Weight Gain in Guinea Pigs
Obesity is an underappreciated welfare issue in pet guinea pigs. These are the most common contributing factors - and the good news is that most are straightforward to address with dietary and environmental adjustments.
Excess Pellets
Many owners overfeed commercial pellets, which are calorie-dense. The typical recommendation for adult guinea pigs is around 1/8 cup of plain pellets per pig per day. Free-feeding pellets is a leading cause of obesity. See the Feeding Calculator for guidance.
Too Many Treats
Fruit, root vegetables (carrots), and commercial treats are high in sugar and should be given very sparingly - a small piece of fruit no more than 1-2 times per week. Daily treat feeding rapidly increases caloric intake beyond what exercise can offset.
Lack of Exercise
A sedentary guinea pig in a small enclosure will gain weight even on a seemingly reasonable diet. Guinea pigs are naturally active animals that need to run, forage, and explore to burn calories. Daily floor time in addition to a spacious cage supports healthy weight management.
Insufficient Cage Space
Guinea pigs in cages below the recommended size have limited opportunity for movement throughout the day. A cage that meets the recommended floor space allows them to run, sprint, and express natural active behaviour - a critical factor in weight management.
Practical Guide
How To Weigh a Guinea Pig Correctly
Accurate, consistent weight data is only useful if your weighing technique is reliable. Follow these steps to get readings you can trust.
- 1 Use a digital kitchen scale. A scale accurate to 1g is ideal. Place a small container or folded towel on the scale and tare (zero) it before placing your guinea pig inside. Food scales that read to 1g are inexpensive and perfectly suitable.
- 2 Weigh at the same time each week. First thing in the morning, before feeding, gives the most consistent readings. Avoid weighing immediately after a large meal or water intake, as this can inflate the reading.
- 3 Keep your guinea pig calm. Place a hide tube or small box on the scale - guinea pigs naturally shelter in enclosed spaces, making them easier to weigh. If they're very wriggly, take three readings and use the middle value.
- 4 Record every reading. Keep a simple weight log - a notebook, spreadsheet, or even a notes app works well. The value of weight monitoring is in the trend, not the single data point. A 50g drop in one week is a yellow flag; a 50g drop over three consecutive weeks is a red flag.
- 5 Note context alongside the weight. Add brief notes on appetite, behaviour, stool quality, and any changes to diet or environment. This information is invaluable when discussing a weight trend with a vet.
📋 Sample Weekly Weight Log
Example data only - not a real guinea pig record. Use this format as a template.
| Week | Date | Weight | Change | Notes |
|---|---|---|---|---|
| Week 1 | 01 Jun | 920g | - baseline | Eating well, active |
| Week 2 | 08 Jun | 927g | +7g ↑ | Normal behaviour |
| Week 3 | 15 Jun | 909g | −18g ↓ | Monitor closely |
| Week 4 | 22 Jun | 922g | +13g ↑ | Appetite returned |
| Week 5 | 29 Jun | 931g | +9g ↑ | Stable, healthy trend |
Tip: A one-off dip (like Week 3 above) is common and not necessarily alarming. It's when the downward trend continues over 2-3 consecutive weeks that you should contact your vet.
Methodology
How Results Are Estimated
Unlike the Body Condition Score-based weight checkers for dogs, cats, and rabbits on this site, guinea pig weight status is estimated by comparing your guinea pig's weight directly against typical gram ranges for their sex and age bracket, since guinea pigs don't vary by breed size the way dogs and cats do.
These are published averages, not limits, and are not breed-specific — some healthy guinea pigs fall outside them.
Adult female (and senior): 700-900g · Adult male (and senior): 900-1,200g (Merck Veterinary Manual)
Birth 100-120g (range 45-120g) · weaning about 180g
A weight above the maximum but within about 15% of it is flagged as above the typical range (the tool's own tolerance band, not a published threshold); beyond that, well above.
Important Limitations
This tool provides an estimate, not a diagnosis. Keep these limitations in mind when reading your result:
- These ranges are general population references; an individual guinea pig's frame size and body condition can place a healthy weight outside the typical range.
- This tool does not perform a hands-on Body Condition assessment — it compares weight alone, which can't distinguish muscle and frame from fat.
- Pregnant sows will naturally weigh significantly more than these non-pregnant reference ranges suggest.
- This tool does not diagnose the cause of unexpected weight — dental disease, illness, or competition for food can all cause weight changes it cannot detect.
- A weight loss of roughly 50g or more in a week is a commonly used rule-of-thumb warning sign (there is no fixed veterinary cut-off) that this tool cannot evaluate on its own. If you are unsure, call your vet.
Worked Example
Example Calculation
How a 950g adult female guinea pig's weight status is assessed.
- Look up the average range for adult females: 700-900g.
- Compare: 950g is above 900g but within the tolerance band (up to about 1,035g).
- Result: this weight is classified as above the typical range, so check body condition (ribs, waist) before drawing any conclusion.
Estimated result: a 950g adult female guinea pig is slightly above the 700-900g average; body condition decides whether it matters.
FAQs
Frequently Asked Questions
Healthy guinea pig weight varies by sex and age. Adult females (sows) average 700g to 900g (roughly 1.5-2 lbs). Adult males (boars) are naturally larger, averaging 900g to 1,200g (roughly 2-2.6 lbs), per the Merck Veterinary Manual. Pups are born at about 100-120g (range 45-120g) and gain weight rapidly. Use the weight checker above to see the typical range for your guinea pig's specific age and sex.
A healthy weight for a guinea pig depends on their sex and life stage. As a general educational reference (Merck Veterinary Manual averages): Adult females: 700g-900g. Adult males: 900g-1,200g. Babies and young adults: still growing, so there is no single range; pups are about 100-120g at birth and roughly 180g at weaning. Individual variation is normal, and body condition matters as much as the number, and a vet is the best person to assess your guinea pig's ideal weight.
Most exotic pet veterinarians recommend weighing guinea pigs once per week. This frequency is sufficient to catch meaningful weight trends - such as a gradual loss that might indicate dental disease or illness - without being excessive. For senior guinea pigs (5+ years) or any guinea pig recovering from illness, weighing twice per week gives more detailed data. Weigh at the same time each week (ideally first thing in the morning, before feeding) for the most consistent results.
Weight loss in guinea pigs can have several causes, including: dental problems (overgrown or misaligned teeth make eating painful), illness or infection (respiratory issues, parasites, kidney disease), competition at food sources (a dominant cage mate may be monopolising food), stress from environmental changes, or inadequate diet. Because guinea pigs instinctively hide illness, weight loss is often the earliest detectable sign that something is wrong. A loss of 50g or more in a week, or a continuing downward trend, warrants a vet consultation. This tool is educational only and does not diagnose the cause of weight loss.
Yes - obesity is a genuine welfare concern in pet guinea pigs and is more common than many owners realise. The most common causes are excess pellets (free-feeding pellets is the leading cause), too many sugary treats (fruit, carrots), and insufficient exercise due to inadequate cage space. Overweight guinea pigs are at increased risk of heart disease, diabetes, joint problems, and reduced lifespan. Dietary adjustment - reducing pellets, eliminating treats, and ensuring adequate floor space - usually helps, ideally under veterinary guidance.
Male guinea pigs (boars) are naturally larger than females. As an educational reference, adult males average about 900g-1,200g (Merck Veterinary Manual). Pups and young adults are still growing, so there is no single range for them; track the trend instead. Some large individuals exceed 1,200g and are still healthy - individual variation exists, so check body condition too. Use the weight checker above with the "Male" option selected for a personalised reference.
Female guinea pigs (sows) are typically smaller than males. As an educational reference, adult females average about 700g-900g (Merck Veterinary Manual). Pups and young adults are still growing, so there is no single range for them; track the trend instead. Pregnant sows will naturally weigh significantly more. Use the weight checker above with the "Female" option selected for a personalised reference.
A sudden weight loss of roughly 50g or more in a single week is a commonly used rule of thumb for acting promptly (there is no fixed veterinary cut-off, so call your vet if you are unsure). First, confirm the reading with a second weigh-in on the same or following day to rule out user error. Then observe your guinea pig closely for: reluctance to eat hay or vegetables, drooling or difficulty chewing, laboured breathing, lethargy, hunched posture, or loose stools. If the low weight is confirmed or any of these signs are present, contact a qualified exotic animal veterinarian promptly. Guinea pigs can deteriorate rapidly when unwell, so early intervention is important. This tool is for educational monitoring only - it does not diagnose the cause of weight loss.
There is no single number, because healthy weight depends on sex, age and build. An adult female well under about 700 g or well over about 900 g, or an adult male well under about 900 g or well over about 1,200 g, is outside the typical average and worth discussing with a vet. A steady downward trend over several weigh-ins matters more than one reading, and a quick drop in a week is urgent.
An average adult female weighs about 0.7 to 0.9 kg (1.5 to 2 lb) and an average adult male about 0.9 to 1.2 kg (2 to 2.6 lb). Breed and build shift the range, so compare your pig against its own weekly trend.
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References
General public resources referenced while researching this tool's topic.
- Merck Veterinary Manual — physiological data for guinea pigs: adult, birth and weaning weights
- Biology and Diseases of Guinea Pigs (PMC) — birth and weaning weights
- RSPCA — general public guinea pig weight monitoring guidance
Editorial Note
This tool is part of PetNurture's educational library. Its formulas and guidance draw on publicly available educational resources, recognised veterinary organisations, and established animal welfare references where appropriate — see the References section below for the specific sources used on this page.
It is provided for general educational purposes and is not a substitute for advice, diagnosis, or treatment from a qualified veterinarian.
Educational Use Notice
Last updated: May 2026The information provided by this tool is for general educational and informational purposes only. Results are estimates, not a diagnosis, and may vary based on your pet's breed, age, health conditions, activity level, diet, and individual factors.
PetNurture does not provide veterinary, medical, or emergency care advice. Always consult a licensed veterinarian or qualified pet care professional regarding your pet's specific health, nutrition, or medical needs.
While we strive to keep calculations accurate and up to date, PetNurture makes no guarantees regarding completeness, reliability, or accuracy. Use this tool at your own discretion.
How we calculate results: This tool uses commonly referenced veterinary formulas, feeding guidelines, and breed-size estimates to provide general educational guidance. Individual pets may have different nutritional, behavioral, or medical needs that are not captured by any generalized formula.
AI Overview & Key Facts
- Purpose: Instant educational estimates to assist pet owners in tracking primary physiological metrics.
- Input Parameters: Weight, sex, and age bracket.
- Reference Guidelines: Ranges are informed by general public guidance from sources such as the AEMV and RSPCA.
- Liability Limitation: Educational estimation only, not a diagnosis. Consult a licensed veterinarian for clinical assessments.
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