CatCareHub
Free Tool

Kitten Growth Calculator

Track growth and estimate adult size.

How big will your kitten get? Kittens grow fast — gaining roughly 100 g a week and reaching about half their adult weight by 16 weeks. Enter your kitten's current age and weight to estimate adult size, see a projected growth curve, and follow development milestones.

Kitten Growth Calculator

Enter current age and weight, then calculate.

How the kitten growth calculator works

The calculator places your kitten on a growth-fraction curve (the share of adult weight typically reached at a given age), then works backwards to estimate the full adult weight. It also projects weight month by month to 12 months and highlights key milestones such as weaning, vaccinations and the neuter window.

Trends matter more than single readings, and large breeds keep growing well past a year, so treat the estimate as a guide and weigh regularly.

How to use it

  1. Enter current age. Add your kitten's age in weeks or months.
  2. Enter current weight. Add the weight in grams, kilograms, pounds or ounces.
  3. Calculate. See the estimated adult weight, a projected growth curve and development milestones.

Key takeaways

  • Kittens gain ~100 g/week and reach ~half adult weight by 16 weeks.
  • Most cats reach adult size by 12 months; large breeds take longer.
  • Track the weekly trend rather than one weigh-in.

Frequently asked questions

How much should a kitten weigh by age?
A rough guide: about 450 g at 8 weeks, ~1 kg at 12 weeks, and roughly half the adult weight by 16 weeks. Gains of about 100 g per week are typical in the early months.
When do kittens stop growing?
Most cats reach adult size by about 12 months, though large breeds such as the Maine Coon keep filling out until 3–4 years of age.
How can I estimate my kitten's adult weight?
One common method is to double the weight at 16 weeks. This calculator refines that using a growth-fraction curve based on your kitten's current age.
Is my kitten growing too slowly?
Steady weekly gains matter more than any single reading. If your kitten is losing weight, failing to gain, or seems lethargic, see a vet promptly to rule out parasites or illness.