Guinea Pig Weight Chart: Healthy Ranges by Age and How to Weigh at Home

Why weighing your guinea pig weekly matters

Guinea pigs are prey animals and hide illness until it is advanced. Weight loss is often the very first measurable sign that something is wrong, appearing before changes in appetite, coat, or behavior. A pig that is quietly eating less because of dental pain or an infection will show it on the scale days or weeks before you notice anything else.

That is why experienced owners and vets recommend a weekly weigh-in for every guinea pig. It takes two minutes, and it turns your scale into an early warning system.

Healthy weight ranges by age

Adult guinea pigs typically weigh between 700 and 1,200 grams. Males (boars) are usually heavier than females (sows), and large breeds can exceed these ranges while staying perfectly healthy. What matters most is not hitting an exact number, it is that your pig's weight stays stable week to week.

• •Newborn pups: 60 to 120 grams
• •2 weeks old: 150 to 250 grams
• •4 weeks old: 250 to 400 grams
• •8 weeks old: 400 to 600 grams
• •3 to 6 months: 600 to 900 grams, rapid growth phase
• •Adult sows: 700 to 900 grams on average
• •Adult boars: 900 to 1,200 grams on average

How to weigh your guinea pig at home

All you need is a digital kitchen scale that measures in grams. Place a small bowl or container on the scale, zero it out, then set your guinea pig inside. Keep sessions calm and short, and weigh at the same time of day each week, ideally before the morning vegetables, since a full stomach can add 30 grams or more.

Write the number down every week. A simple notebook or spreadsheet works, and seeing the trend line is far more useful than any single reading.

When weight changes mean a vet visit

Small daily fluctuations are normal. The red flags are patterns and larger swings. As a rule of thumb used by exotic vets, a loss of around 50 grams or more in a week, or steady decline over two to three weeks, warrants a veterinary check, even if your pig seems otherwise fine.

Weight loss in guinea pigs is most often linked to dental problems, infections, digestive issues, or pain. Because they hide illness so well, the scale often catches what your eyes cannot.

• •Loss of 50 grams or more in one week: book a vet visit
• •Loss of 100 grams or more, or any loss with reduced appetite: urgent, see a vet promptly
• •Steady decline over several weeks, even in small steps: vet check, common with dental disease
• •Rapid gain in a sow living with a boar: consider pregnancy
• •Pups that stop gaining or lose weight in the first weeks: vet check, they should grow steadily

Is my guinea pig overweight?

An overweight pig usually got there through too many pellets, sugary treats, or fruit, combined with too little exercise. You should be able to feel (not see) the ribs with light pressure, and the belly should not drag on the ground. If your pig is overweight, cut back pellets to a measured tablespoon or two per day, remove fruit and treats, keep unlimited timothy hay, and increase floor time. Never crash-diet a guinea pig; lose weight slowly over weeks.

The Wheeky Guide app helps with both sides of weight management: its food database of over 2,000 items shows which foods are safe daily versus occasional, and its care checklists make weekly weigh-ins part of a routine you will not forget.