Puppy Weight Calculator

Updated November 2026 · free, works in your browser

To estimate how big your puppy will get, divide its current weight by its age in weeks and multiply by 52. A 12-week-old puppy that weighs 5 kg (11 lb) would be projected at about 21.7 kg (47.8 lb) as an adult. The calculator above does this instantly and adds a likely range, because every puppy grows at its own pace.

How to use the puppy weight calculator

1. Weigh your puppy on a scale. For small puppies, weigh yourself holding the puppy and subtract your own weight.
2. Enter the weight and choose kilograms or pounds.
3. Enter the puppy's age and choose weeks or months. The tool accepts ages from 6 weeks to 12 months.
4. Read the estimated adult weight, the likely range and the average weekly gain so far.
5. In the full version, copy a link to keep or share your result.

How it is calculated

The tool uses a widely used rule of thumb: adult weight ≈ current weight ÷ age in weeks × 52. In other words, it takes the average weight your puppy has gained per week so far and projects it over one year, the age when many dogs are close to their final size.

• Current weight is the weight you enter, converted internally to kilograms (1 kg = 2.20462 lb).
• Age in weeks is the age you enter; months are converted with 1 month = 52 ÷ 12 weeks.
• 52 is the number of weeks in a year.
• The likely range is the estimate minus and plus 10%, a simple margin used by this tool to show that the result is approximate.

Puppies do not gain weight at a constant rate. Growth is fast early on and then slows, so the estimate is less reliable for very young puppies and for large and giant breeds, which keep growing for longer. Breed, parents' size, sex, diet and neutering can all change the final weight.

This is not medical advice. The result is a rough estimate, not a diagnosis. Ask your veterinarian about your puppy's growth, feeding and ideal body condition.

Typical adult size groups

Sources group dogs by adult weight slightly differently. These are commonly used rough groupings.

Frequently asked questions

How accurate is a puppy weight calculator?

It gives a ballpark figure. Because growth slows with age, the simple weekly-rate method can overestimate for some puppies and underestimate for others. Treat the range as a guide, not a promise.

At what age is a puppy fully grown?

Small breeds often reach adult size around 9 to 12 months, while large and giant breeds can keep filling out for 18 months or longer.

Does the calculator work for mixed breeds?

Yes, but mixed breeds are harder to predict, especially when the parents' sizes are unknown. Re-check every few weeks, as new measurements improve your picture of the growth trend.

How often should I weigh my puppy?

Many owners weigh weekly during the first months. Regular weights help you notice whether growth is steady, and your vet can tell you what is normal for your puppy.

Is it a problem if my puppy is above or below the estimate?

Not necessarily. The estimate is only a projection. If you are worried about rapid gain, slow gain or your puppy's body shape, talk to your veterinarian.

Planning ahead as your puppy grows

Knowing your dog's likely adult size helps with practical plans beyond the vet, such as the right crate and carrier, and later, travel. Many airlines and pet-friendly hotels set weight or size limits for dogs, so a realistic estimate helps you pick suitable accommodation and check pet policies before booking a trip together.