Kitten Growth Calculator (Age & Size Estimator)
Estimate a kitten’s age from weight and simple milestones, then predict adult size/weight using a basic growth curve.
Quick answer
Fast rule (rough)
Early on, many kittens follow a rough pattern: about 1 lb per month (up to ~6 months). This tool blends that with optional milestones and shows a range.
Growth varies by breed, nutrition, and health. Use this as an estimate.
Inputs
Best estimate comes from a recent weigh-in.
Enter 0 if you don’t know the age.
Optional milestones (helps age estimate)
Optional: frame / sex
Slightly adjusts adult-weight range.
Small effect; individual variation is bigger.
Important note
Growth varies by breed, nutrition, parasites, and health. If a kitten is not gaining weight, seems lethargic, has diarrhea/vomiting, or is very underweight, contact a veterinarian promptly.
How this calculator works (formulas)
Age estimate
- Weight-based estimate: ~1 lb per month up to ~6 months (rough heuristic).
- Milestone estimate: teeth, eye color changes, weaning, and mobility give a second estimate.
- We blend both and show a range because kittens vary.
Adult weight prediction
We estimate what fraction of adult weight a kitten typically has at a given age, then invert it:
AdultWeight ≈ CurrentWeight ÷ AdultWeightPercent(age)
The calculator uses simple age points and linear interpolation (a basic growth curve).
FAQ
How can I estimate a kitten’s age?
Weight can give a rough idea early on, but milestones like teeth, eye color changes, and weaning often improve accuracy. This tool combines both and gives a range.
Is predicted adult weight accurate?
It’s an estimate. Genetics, breed, nutrition, and health can change growth patterns. Use it as a planning range — not a guarantee.
When should I worry about kitten growth?
If a kitten isn’t gaining weight, seems weak or dehydrated, or has persistent diarrhea/vomiting, contact a veterinarian. Young kittens can decline quickly.