Planning a cat tree, a carrier or a feeding amount is easier with a figure for the adult weight. This calculator divides the current weight by the share of growth already completed at this age in weeks, shows the projected adult weight as a range, reports how wide that range is, and checks whether an adult weight you already know falls inside it.
There is only one formula here, current weight divided by the share of growth completed, and the numbers you typed are repeated on the formula line of the result. The tool does not choose the percentage for you. Judging life stage and when growth has finished is work your veterinarian does for the individual cat, following the feline life stage guidance from the American Association of Feline Practitioners (AAFP) and AAHA. Guidance current as of October 2026.
No recognized standard table of growth curve coefficients by breed and week exists. This tool therefore offers no breed selector, and it does not score body condition or calculate feeding amounts. The result is an extension of the percentage you entered rather than a forecast, and the error is large. This tool is for reference only and does not replace veterinary care. Contact your veterinarian right away if you notice symptoms or suspect a problem.
Frequently Asked Questions
Kitten weight changes week by week for the first several months, so grouping by month hides large differences inside the same month. Weeks make it clear which point in the growth curve the weight belongs to.
It is optional. If you know the adult weight of the mother or a littermate, enter it. It does not change the calculation and only tells you whether that weight falls inside the projected range.
A wide percentage range produces a wide weight range. A wide result means the information you have does not justify a narrower figure, so if you need a tighter number, ask your veterinarian for a body condition assessment as well.