How does the pet growth calculator work?

It estimates what percent of adult size your pet has reached at the entered month, then divides current weight by that percent. Example: 18 lb at 5 months on the medium dog curve is about 62% grown.

Is this exact for every breed?

No. Breed, sex, nutrition and health can change growth. Use it as a planning range and confirm concerns with your vet.

Why does dog size matter?

Small dogs usually reach adult size around 12 months, medium around 15, large around 18 and giant around 24. The size setting picks the matching curve.

Pet Growth Calculator

Written by FurStage Editorial TeamReviewed by FurStage Evidence ReviewReview date: July 16, 2026

Estimate adult weight from current age and weight. Dog curves differ by expected adult size: small dogs mature around 12 months, medium 15, large 18 and giant 24.

Animal

Expected adult size

Current age (months)Current weight

Enter current age and weight to estimate adult size.

General guidance only — not veterinary advice and not for emergencies. Consult your vet for any health decision. Sources: Salt et al. (2017), WSAVA.

Call your vet now if your pet has trouble breathing, collapses, has severe pain, repeated vomiting, seizures, heavy bleeding, or suddenly cannot stand.

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Frequently asked questions

How does the pet growth calculator work?: It estimates what percent of adult size your pet has reached at the entered month, then divides current weight by that percent. Example: 18 lb at 5 months on the medium dog curve is about 62% grown.
Is this exact for every breed?: No. Breed, sex, nutrition and health can change growth. Use it as a planning range and confirm concerns with your vet.
Why does dog size matter?: Small dogs usually reach adult size around 12 months, medium around 15, large around 18 and giant around 24. The size setting picks the matching curve.