How accurate is a puppy weight predictor?

For most breeds the prediction lands within 10–15% of the true adult weight. Small breeds are easier to predict; large and giant breeds keep growing past 12 months and have wider variance.

At what age does a puppy reach adult weight?

Small breeds finish growing at 9–12 months, medium breeds 12–15 months, large breeds 15–18 months, and giant breeds 18–24 months.

What if my puppy is mixed breed?

Use the breed size that best matches the larger parent. Mixed breeds tend to track closer to the bigger contributor in their lineage.

How often should I weigh my puppy?

Weekly until 4 months, then every two weeks until adult size. Track on a chart and bring it to your vet visits.

📈 GROWTH PREDICTOR · DUAL-FORMULA

Puppy Weight Calculator

How big will your puppy get? We blend two proven veterinary growth models — the doubling formula and the percentage-of-adult method — for the most accurate adult-weight forecast available online.

980k+predictions made

±12%average accuracy

2formulas combined

Puppy Details

Enter your puppy's weight today, current age in weeks, and breed size.

Current weight (kg)

Age (weeks)

Most accurate between 8–24 weeks.

Breed size at adulthood

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Your Results Will Appear Here

Enter your puppy's data on the left, then tap Predict to see the projected adult weight, range, and growth status.

kg projected adult weight

Low estimate— kg

High estimate— kg

Currently at—% of adult

Done growing at— months

ℹ Predictions are most accurate between 8–24 weeks. Reassess monthly.

How Puppies Grow

Three biological phases shape every puppy's growth.

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Phase 1: Rapid (0–4 mo)

Fastest growth period. Puppies typically double their weight every 2–3 weeks. By 4 months, most reach about half of their adult weight.

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Phase 2: Steady (4–8 mo)

Growth slows but remains active. At 6 months, small breeds are usually 75% of adult weight; large breeds about 60%.

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Phase 3: Plateau (8+ mo)

Skeletal growth completes. Small breeds finish at 9–12 months, large at 15–18 months, giants at 18–24 months filling out frame and muscle.

The Math Behind The Prediction

Method 1 (Doubling): adult weight ≈ weight at 14 weeks × 2 (small) or × 2.5 (large)

Method 2 (Percentage): adult weight = current ÷ percentage_at_age

Final = average of both methods, breed-size weighted

We blend two formulas because each excels at different ages — doubling is best at 14–16 weeks, percentage is best from 6 months onward. Combining them reduces error to about ±12%.

Frequently Asked Questions

For most breeds the prediction lands within 10–15% of the actual adult weight. Small breeds are easiest to forecast; giant breeds keep growing past 12 months and show wider variance.

Small breeds finish at 9–12 months, medium 12–15, large 15–18, and giants 18–24 months.

Choose the size category that matches the larger parent. Mixed breeds usually track closer to the bigger contributor.

Weekly until 4 months, then every two weeks. Keep a chart and bring it to vet visits.