Everything you need to know about your guinea pig and their weight too fat too thin

You may already be an expert on cavy care, from clean cages to the perfect diet. But not many piggy parents know that weighing their furry potatoes every wheek is a great way to monitor their wellbeing. Taking the time to regularly pop your piggy on the scales is a crucial part of cavy care and a helpful way to keep an eye on their general health and catch anything unusual early on.

If you’re a little unsure about a healthy weight for guinea pigs, how to get guinea pigs to lose weight, how to get guinea pigs to gain weight, and - most importantly - how to even get them on the scales, don’t worry. This guide to guinea pig size has got all the info you could need.

How Big Is a Full-Grown Guinea Pig?

Just like us humans, guinea pigs come in all shapes and sizes. And while male guinea pigs, also called boars, are usually a little bigger and heavier than female guinea pigs, or sows, an adult piggy’s size and weight vary depending on their breed and age, and also their diet and pigsercise. A normal weight for one piggy could be an underweight piggy of a different breed. The healthy weight for guinea pigs depends on a lot of factors.

Let’s have a look at some general guidelines for a healthy weight for guinea pigs depending on their gender.

An image to show the average weight and size of guinea pigs

How big do female guinea pigs get?

As you already know, there’s no one size fits all for piggies. But as a general rule of thumb, female guinea pigs are a little smaller and lighter than the males - all depending on their breed and age. An average weight for a grown-up female guinea pig is around 2 lb to 2.5 

 lb, or 900 g to 1100 g. Today, many pet parents find that their guinea pigs weigh in the top weight range, especially for female guineas. 

This female guinea pig weight chart is a great point of reference for the growth journey your floofs will go on:

A graph to show the weight of your guinea pig as it grows

How big do male guinea pigs get?

Male piggies are normally a little bigger and heavier than their female counterparts. A healthy weight for boars is between 2.2 lb and 3.5 lb, or 1000 g to 1500 g. As always, these numbers vary, depending on the breed and age of the male guinea pig. So bear in mind that some guinea pigs may be lighter or heavier than these averages but still be perfectly healthy. 

If you keep track of your piggies’ weight every week, you’ll soon know what a good weight for them is. And you’ll be able to spot anything wrong so much quicker. After all, as a piggy parent, you know your fluffballs best!

Here’s your male guinea pig weight chart, a fantastic point of reference:

A graph to show the weight your guinea pig should be with age

A Guinea Pig’s weight is linked to their breed

Your guinea pigs’ breed makes a big difference to their size. Smaller breeds, like Americans, weigh less because there’s less piggy to weigh. Larger breeds, like Peruvians, not only put more piggy on the scales, they also bring long hair along. Among the 13 guinea pig breeds that the American Cavy Breeder Association, you’ll find lots of variation for size and weight of the adorable floofs.

On a funny note, we’d just like to confirm that skinny pigs aren’t actually skinnier than other guinea pigs. Yep, they lack the luscious locks of some of their cavy companions, but they’re not far behind when it comes to size or weight. The breed’s name is simply a reference to the amount of skin you’re seeing (and, let’s be honest, it’s a lot nicer than calling them naked guinea pigs!).

Here’s how the average weight of our most popular guinea pig breeds varies:

  • Abyssinian: 2 lb to 3 lb, or 900 g to 1400 g
  • American: 1.5 lb to 2.5 lb, or 700 g to 1100 g
  • Peruvian: 2 lb to 3 lb, or 900 g to 1400 g
  • Texel: 1.5 lb to 2.5 lb, or 700 g to 1100 g

Two guinea pigs different sizes and weight

Who is the biggest guinea pig?

The biggest pet guinea pig breed is the Rex with up to a whooping 18 inches in length and can weigh up to 3 lb or 1400 g. These floofy-haired pigs are larger than most of their piggy pals, and because of that, their piggy parents should take extra care when it comes to weight checks and diet. The Rex guinea pig is known to gain weight quickly, so a weekly check-up can help keep them at a comfortable and healthy weight. Even if it’s extra hard to resist feeding those sweet piggy faces treats.

If you’ve never heard of a Cuy guinea pig, well, now you’re in for a treat. These absolutely massive guinea pigs are often twice as large as our pet piggies, weighing around 4 lb to 8 lb, or 1800 g to 3600 g. It probably won’t come as a surprise that these large pigs were bred as a food source in Peru, and although some are kept as pets in North America, Cuys are extremely skittish and have a much shorter lifespan than pet guinea pigs. But aren’t they just magnificent?

Tri coloured cuy guinea pig on grass

Who is the smallest guinea pig?

On our list of smallest guinea pig breeds, we’ve got the Texel and the American guinea pig. Americans only get to around 8 in or 9 in (20 cm to 22.5 cm), so there can be a size difference of 10 in between an American and a Rex! The sweet Texel is in a similar boat, at around 8 in to 10 in (20 cm to 25 cm).

Both breeds come in at around 1.5 lb to 2.5 lb, or 700 g to 1100 g, and it’s a good idea to monitor their weight closely. Piggy parents wouldn’t want their smaller floofs to become underweight or overweight. It’s really a fine line with our precious pets.

a small sized texel guinea pig

How Big Are Baby Guinea Pigs?

If you’ve never seen a baby guinea pig (treat yourself and look up some adorable photos!), you’ll be surprised to find that they arrive in the world with a full coat and ready to go. Baby guinea pigs could survive on their own after just a week (not that they ever should!), so these tiny floofs grow pretty quickly - and so does their weight.

A newborn guinea pig can arrive in the world at anywhere between 2 oz (60 g) and 4 oz (120 g). Just like adult guinea pigs, a baby piggy’s weight varies depending on their breed. Then, as they get bigger quickly, they can pack on an extra 1 oz to 1.5 oz (30 g to 50 g) per week in the first 8 weeks of their lives.

When they reach 16 weeks of age, most baby guinea pigs will be with their new piggy families already. At this stage, a healthy piggy weight is between 13 oz and 17 oz (360 g and 480 g). Adding another few weeks of baby piggy growth to this, and a healthy weight for guinea pigs at 6 months is around 17.5 oz to 25 oz (500 g to 700 g).

Just before a baby piggy reaches one year of age, they’re fully mature - meaning they’re done growing (unless you feed them too many treats, in which case they’ll grow sideways). At that point, they should also reach a good average weight for their breed. Younger guinea pigs are very active with lots of popcorn parties, so it’s normal for them to be a little lighter than their older piggy friends.

If you notice a sudden drop or rise in your sweet baby piggies’ weight, it’s a good idea to speak to a vet of your choosing. It could be a sign that your floofs aren’t feeling their best, so it’s important to catch this early.

a tri coloured small baby guinea pig

Why Should I Watch My Guinea Pig’s Weight?

It’s simple, really. Like all animals, a guinea pig’s weight is an important indicator of their general health. Let’s face it, guinea pigs are generally walking stomachs - they eat non-stop! But when a piggy is unwell, they tend to eat less, meaning that they burn more body fat for energy and start to lose weight. 

As prey animals, guinea pigs are generally very adept at hiding symptoms of illness in order to avoid appearing weak to predators. But the one sign of illness that they’re unable to conceal is weight loss.

A picture of a weighing scale

By popping your guinea pig on the scales on a regular basis, you can keep track of their weight and well-being. That way, if you notice an unexpected or worrying change, you can take appropriate action by making an appointment with a vet for a check-up. 

Another thing to bear in mind is that guinea pigs are sensitive little souls who can become depressed - for instance, when they lose a cage mate. If your piggy is feeling blue, this can cause them to stop eating and lose weight too.

How Exactly Should I Weigh My Guinea Pig?

If you already have guinea pigs, you’ll know that these tiny tornadoes rarely stop hopping about their homes - apart from nap time, of course. But how on earth are you meant to pop them on a scale?

Never fear, brave piggy parent, we’ve got a step-by-step guide to make the wheekly weighing sessions a success with every cavy!

Step 1: Choose Your Scales

When it comes to your piggy scales, you’ve got the choice of analog or digital scales, and it’s really down to your own preference. Some cavy carers prefer digital scales because there’s no chance of misreading it. Others prefer good analog scales.

When you choose your piggy scales, remember that there needs to be enough room for your pets on it. Whether the scales come with a container on the top or you add your own, piggy safety is key to finding the right scales.

Once you’ve found the right set for you and your floofs, it’s a good idea to store them near your piggies’ palace and keep them for the weekly weighing only. After all, if you’re using your baking scales, there’s a chance your pigs could find a bit of leftover cookie batter - or they could leave a little something for your next baking session on the scales. You see where we’re going with this, right?

Now you’ve got the tools, let’s see how you can prepare for the weighing sessions!

examples of scales for weighing your guinea pigs

Step 2: Get Ready to Weigh!

Before you get your pigs, make sure to pop the scales on a safe, flat surface. Some of our furry friends won’t want to stay on the scales, so it’s best to prepare for them hopping off. For this reason, it’s also helpful to pop your piggies in a box when weighing, so they’re secure. Remember to take off the box’s weight from your final reading.

If you’re sure that everything’s set up safely, it’s time to get the pigs!

Step 3: Keep Track of Their Weight

Track your guinea pig’s weight by entering the results for each weigh-in on a calendar, spreadsheet, notebook or an app on your phone. If you need to take your piggy to the vet, don’t forget to also take along a copy of their weight tracker to help with any medical assessments.

a guinea pig being examined by the vet

What about tracking my pregnant guinea pig’s weight?

A pregnant sow almost doubles her pre piggy pregnancy weight - and no wonder, if she’s carrying several baby floofs around! During this time, it’s a good idea to keep a close eye on the piggy’s weight to make sure she eats enough and has everything she needs. The weight is also a good indicator of any reason for concern and a vet visit.

A pregnant sow needs some extra support during this time, since being piggy pregnant is hard work. More than ever, she’ll need vitamin C in her diet and lots of leafy greens to soak up the good nutrients. High-quality pellets also help with this.

Your female piggy will get pretty big, so it’s important to keep her in a comfortable and quiet environment, so she can rest and relax. Some piggy parents like to put their pregnant pigs in with another female, so they have a friend who cares for them. Remember that guinea pigs can get pregnant shortly after giving birth, so keep your male piggies separate.

Even if you feel like your pregnant piggy has everything she needs and is gaining weight nicely, it’s important to take her for regular check-ups at a cavy-savvy vet’s!

What If I Can’t Weigh My Guinea Pig?

In a perfect world, every guinea pig parent would have a set of weighing scales close to hand and we’d recommend that you buy an inexpensive set if possible. As we’ve already explained, regular weigh-ins are the most accurate way to track your guinea pig’s weight.

However, the truth is that we don’t live in a perfect world. So if you can’t get hold of a set of scales for whatever reason, you can get a pretty good idea of whether your guinea pig is losing or gaining weight by keeping a close eye on them and handling them often.

Measuring your guinea pig’s ‘heft’ (another word for ‘weight’ or ‘size’) is a useful way of recognizing if they’re healthy or not. You can do this by holding your furball and gently checking around their spine, hips and ribcage. 

A kavee employee holding two guinea pigs

You should be able to feel the outline of these bones through their fur and body fat. If you can’t feel any bones at all through your piggy’s podge, they may be overweight. 

On the other hand, if their hips, ribs and spines appear to be jutting out a bit too much then your guinea pig may be underweight.

There are also other signs that may indicate a weight problem - if your piggy is struggling to walk, their stomach touches the floor when they’re standing or they appear to have less energy, then something may be amiss. 

If you have a long-haired guinea pig, remember that those flowing locks can make it harder to spot weight changes as well as other signs such as thinness and protruding ribs - which makes it even more important to do regular weigh-ins.

To give you a visual idea of your guinea pig’s size, check out this handy Guinea Pig-Size-O-Meter infographic from pet food manufacturers association, PFMA .

a guinea pig size meter

a guinea pig size metre continued

How Often Should I Weigh My Guinea Pigs?

Weighing a guinea pig once only tells you how much they weigh at that precise moment. It doesn’t alert you to any potential weight gain or loss. 

For that reason, it’s important to make regular weigh-in sessions part of your piggy’s care routine. How often you weigh your piggy depends on which stage of life they’re at. 

Here are some easy-to-follow tips for creating a successful guinea pig weight tracker routine:

  • Be organized, create a schedule and stick to it. 
  • If your guinea pig is in good health, perform weekly weigh-ins as a routine health check
  • Weigh your piggy at the same time and day each week to keep tracking consistent
  • If you have newborn baby guinea pigs, weigh them daily over the course of their first few weeks and then progress to weekly weigh-ins to ensure they’re gaining weight.
  • If you’re concerned about your guinea pig’s health for any reason, weigh them daily so that you can quickly recognize - and act on - any worrying weight changes.

To help you keep track of your guinea pig’s weight, we’ve produced a free Kavee guinea pig resource pack, which you can print and use. 

Routinely track your guinea pig’s weight on a graph so that it is easy to visualize and quickly notice any changes. We’ve included some examples in the pack to help get you started!

My Guinea Pig’s Weight Has Changed. Should I Worry?

A piggy’s weight can go up and down a little, depending on how full their stomach is or how they’re feeling that day - just as it does for us humans. But what exactly is considered to be an acceptable weight change, and when might a weight loss or gain actually be cause for concern?

  • If your piggy’s weight either drops or increases by 25g (0.8oz) in a week, then try not to worry. Small changes in an adult piggy’s weight are actually pretty normal, so just continue weighing your piggy weekly to keep track of things. However, if you notice that your piggy’s weight routinely drops or gains 25g (0.8oz) between weigh-ins, then it may be time for a visit to see the vet to check everything’s in order.
  • If you notice that your piggy has lost or gained 50g (1.7oz) it’s important to keep a close eye on them. Start weighing them daily so that you can quickly recognize any more sudden weight changes and get them checked out by a vet if necessary. 
  • If your guinea pig’s weight drops or increases by 75g (2.6oz) it’s time to take action as that’s a pretty big change. Get them booked in with the vet. 
  • A sudden weight loss or gain of 100g (3.5oz) would be considered an emergency in terms of your guinea pig’s health, and you should take them to the vet as a matter of urgency. Check our list of recommended cavy vets in the USA to guide your choice. 
a guide to weight changes in guinea pigs

Help, My Guinea Pig Is Too Big!

It’s easy for our pet piggies to gain too much weight. In the wild, piggies forage all day and run across huge grassy areas. In our homes, they’re limited to their cage. It’s easy for our furry potatoes to become couch potatoes and simply spend their days in bed, snacking away.

If you notice your floofs are getting a bit too round, think about their environment. Do they have enough space to run about or could you update their cage? Does the cage setup include interesting toys, hideys, and forage opportunities to stimulate them and encourage more pigsercise? Are they eating the wrong food that could make them put on lots of weight, like fresh foods that are high in sugar, including fruits and carrots?

If you’re wondering how to get guinea pigs to lose weight, your quickest and best shot is more exercise and the right diet. Upgrading their cage and also making time for daily out-of-cage play sessions are a great starting point. Often, however, this can also be an indication of underlying health issues. To be on the safe side, you can take your pigs to the vet and discuss your concerns. They’ll be able to help you make a weight loss plan, if needed, and also make sure your floofs are healthy otherwise.

An overweight piggy, just like any other animal or human, is at a much higher risk of catching other health issues, like

  • Heart problems
  • Diabetes
  • Back pain
  • High blood pressure
  • Digestive problems
  • Bumblefoot
  • Urine scald (hutch burn) caused by urine soaking into the guinea pig’s fur and skin because they’re immobile
  • Pressure ulcers 
  • Fly strike and other pests, which will be attracted to a dirty guinea pig who is too big to groom themselves properly
Possible complications for guinea pigs with obesitity

How to get guinea pigs to lose weight

If your piggy consumes more calories than they burn through activity, they will gain weight. There are several ways you can help your guinea do the opposite and lose weight:

  • Don’t exceed the daily recommended amount of food (portioned pellets, fruits and veggies)
  • Limit the amount of fruit and carrots you feed your guinea pigs as they’re full of sugar
  • Avoid feeding your guinea pig unhealthy snacks and treats which are usually high in sugar and other unhealthy ingredients
  • Take a look at our free Kavee care sheets for more guidance on how to feed your guinea pig a healthy diet
  • Provide daily floor time (two hours a day if possible) to increase your guinea pig’s exercise and activity levels
  • House your guinea pig in the largest cage possible to provide plenty of space for exploring (bear in mind that small pet shop cages prevent piggies from exercising)
  • Provide chew toys and other enrichment opportunities such as our Kavee ramp and loft kit
  • Double-check any female piggies to see if they’re pregnant - in which case they’ll need extra nutrition and support
a happy guinea pig in a sleeep sack

Help, My Guinea Pig Is Too Thin! What Should I Do About It?

Losing weight and becoming underweight can be a real concern for guinea pigs - they can lose weight rapidly, which puts them at a higher risk of developing dangerous health complications, including:

  • Decreased immune function
  • Malnutrition and vitamin deficiencies
  • Anemia
  • Growth and development issues
  • Higher risk recovery from surgical procedures
  • Hypothermia due to the guinea pig not having enough body fat to keep warm
  • Fur, skin, and teeth problems
possible complications for underweight guinea pigs

Why is my guinea pig losing weight? 

If you've noticed your guinea pigs are losing weight, it’s a cause for concern. Our furry friends eat all the time because of their quick metabolism, so they shouldn’t be losing weight without a reason. If you notice your piggies are getting smaller, it could be because of

  • the wrong diet: do they have access to a big pile of hay all the time? Do you feed healthy veggies and high-quality pellets every day?
  • lack of food: some new cavy carers don’t realize that their pigs need food all day long. Make sure hay is always available, and other healthy snacks  and pellets are available throughout the day
  • stress: piggies are stressed easily, either by rough handling, a busy environment, or unsuitable living conditions - and that can affect their appetite. Can you move them to a quiet, large cage that lets your floofs relax, so they can eat safely?
  • health issues: the real troublemaker when it comes to losing weight are health issues. Anything from an infection to poor dental health can have an impact on your piggies’ weight, so a vet visit can help you rule any of these out

When we care for our piggies correctly by providing a great cage and environment, giving them a good diet, grooming them regularly, and handling them without causing stress, the cute cavies thrive and should have a healthy weight for guinea pigs. So if you notice that something’s off about their size, it’s time to start investigating!

How to help guinea pigs gain weight

First things first; check your guinea pig’s food intake. Are they really getting a great diet with sufficient nutrition or do you need to increase their calorie intake? If you’re confident they’re getting the right food, you can add a few healthy treats that help guinea pigs gain weight. When you first introduce new snacks, remember to add them in gradually so there’s no upset tummies.

Oat flakes and small slices of banana are some of the best food for guinea pigs to gain weight, though they also come with some additional cavy care needs. When piggies eat oat flakes, they need to drink more, because the flakes soak up the water they’ve drunk. Bananas are healthy but high in sugar, so be careful about feeding more than the odd slice. Some piggies may be suspicious of these new foods at first, so it can take a few tries until they like them.

Make sure they has access to these foods every day to help them your guinea pigs gain weight:

  • hay: it’s the key component to a brilliant piggy diet, and a different type of hay can help your guinea pigs gain weight. Timothy hay is the best choice for piggies, but you can add some oat hay to their diet while they’re building up a little piggy chunk
  • veggies: piggies have them every day, and you can add an extra slice of carrot to their diet while they’re gaining weight
  • pellets: there are lots of guinea pig pellets out there, and choosing a high-quality brand will help your piggies reach and maintain a healthy weight for guinea pigs

But food is not the only lifestyle choice that makes a big difference in your piggies’ wellbeing. Keeping them at a comfortable temperature between 65 °F to 73 °F (18 °C to 23 °C) means the furry friends don’t need to use up extra energy to stay warm - which could lead to weight loss.

Any injury or illness can also affect their appetite, so it’s a good idea to check them for anything unusual regularly. Teeth issues, in particular, are a real culprit when it comes to weight loss. And if your piggies are off their food, it’s important to act quickly because the situation is critical. If in doubt, contact your vet and let them show you how to syringe feed your floofs until they’re better.

Weight loss in piggies is not to be taken lightly, and it’s a good idea to keep an eye on their eating habits as well as their weight.

how to prevent weight loss in guinea pigs

FAKs About How Big Do Guinea Pigs Get

How big is a full-grown guinea pig?

The average weight for a female guinea pigs is around 2 lb to 2.5 lb, or 900 g to 1100 g. A healthy weight for male guinea pigs between 2.2 lb and 3.5 lb, or 1000 g to 1500 g.

Remember that these numbers are just a point of reference because every pig is different.

Do guinea pigs lose weight as they get older?

Yes, guinea pigs often lose weight when they get older because their metabolism slows down. When they eat less, they lose weight. Some of the best food for guinea pigs to gain weight includes oat hay, though if they lose a lot of weight, older piggies should see a vet.

What is the best food for guinea pigs to gain weight?

The best food for guinea pigs to gain weight is oat hay, the right veggies, like a slice of carrot, and high-quality pellets. A cavy-savvy vet can help set up a dietary plan for healthy weight gain for your pigs.

How big do female guinea pigs get?

Normally, an adult female guinea pig weighs around 2 lb to 2.5 lb, or 900 g to 1100 g. They’re usually between 8 in and 10 in, or 20 cm to 25 cm, long.

Remember that guinea pigs come in all shapes and sizes, like humans, so you may meet some female guinea pigs that are bigger or smaller than this.

How big do male guinea pigs get?

Adult male guinea pigs usually weigh around 2.2 lb and 3.5 lb, or 1000 g to 1500 g. They’re often a little bigger than female guinea pigs, though different piggy breeds come in different sizes.

About the author

Fine Mayer

Fine is an ardent animal lover and particularly enjoys the company of her three guinea pigs, Tiberius, Ziri, and Henry. With more than 15 years of pigsperience, she knows the ins and outs of guinea pig care. Today, Fine lives in Glasgow, Scotland, with her three pigs and three noisy birds.

Guinea pig careGuinea pig health

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