Puppy Weight Calculator
Predict your puppy's adult weight from its current age and weight.
Enter your values
Enter the puppy age in months.
Enter the current weight in kg.
Choose one of: Toy (under 5 kg adult), Small (5-11 kg), Medium (11-25 kg), Large (25-45 kg), Giant (45 kg+).
Results update instantly as you type — no submit needed. Your values are remembered on this device, and the shareable link reopens the calculator with exactly these numbers.
- Predicted adult weight
- 13 kg (28.7 lb)
- Growth completed
- 62%
- Weight still to gain
- 5 kg
- Fully grown at
- about 13 months
- Likely adult range
- 11.1 - 15 kg
Working
- 18 kg / 0.615 growth fraction = 13 kg adult
| Age | Expected weight | % of adult |
|---|---|---|
| 2 months | 5.3 kg | 41% |
| 3 months | 6.8 kg | 53% |
| 4 months | 8 kg | 62% |
| 6 months | 9.6 kg | 74% |
| 8 months | 10.7 kg | 82% |
| 10 months | 11.4 kg | 88% |
| 12 months | 11.9 kg | 91% |
| 18 months | 12 kg | 93% |
Quick answer
Puppies reach a predictable fraction of adult weight at each age, and the fraction depends on breed size. Small breeds finish by 10 months, giant breeds take up to 24.
adult weight = current weight / growth fraction at this age
At a glance
| What it does | Predict your puppy's adult weight from its current age and weight. |
|---|---|
| Category | Pets |
| Inputs needed | Puppy age, Current weight, Expected breed size |
| Main output | Predicted adult weight |
| Formula | adult weight = current weight / growth fraction at this age |
| Cost | Free — no sign-up, no download |
How to use the Puppy Weight Calculator
- 1Weigh your puppy and note its exact age in months.
- 2Pick the breed size band — for a mix, use the larger parent as a guide.
- 3Compare the monthly chart with real weigh-ins to see whether growth is on track.
Inputs explained
- Puppy age(months)
- Enter the puppy age in months.
- Current weight(kg)
- Enter the current weight in kg.
- Expected breed size
- Choose one of: Toy (under 5 kg adult), Small (5-11 kg), Medium (11-25 kg), Large (25-45 kg), Giant (45 kg+).
Worked example
Using the values the calculator loads with:
Inputs
- Puppy age4 months
- Current weight8 kg
- Expected breed sizeMedium (11-25 kg)
Results
- Predicted adult weight13 kg (28.7 lb)
- Growth completed62%
- Weight still to gain5 kg
- Fully grown atabout 13 months
- Likely adult range11.1 - 15 kg
- 8 kg / 0.615 growth fraction = 13 kg adult
Frequently asked questions
How accurate is a puppy weight prediction?
Within about 15% for purebred puppies of a known size band. Mixed breeds vary more, especially when the parents differ in size.
Should I free feed a growing puppy?
No, particularly for large breeds. Overfeeding accelerates growth and raises the risk of hip and joint problems later.
What do I need to enter into the Puppy Weight Calculator?
Just 3 values: puppy age, current weight, expected breed size. Every field starts with a realistic example, so you can change one number at a time and watch the result update instantly.
How does the Puppy Weight Calculator work out the answer?
Puppies reach a predictable fraction of adult weight at each age, and the fraction depends on breed size. Small breeds finish by 10 months, giant breeds take up to 24. It applies the formula adult weight = current weight / growth fraction at this age and shows the working so you can check each step by hand.
Is the Puppy Weight Calculator free, and do I need an account?
It is completely free with no sign-up, no download and no usage limit. Everything is calculated in your browser, so the numbers you type never leave your device.
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.